Abstract:
Methods and apparatus are provided for retaining a hinge shaft of a check valve with a bushing. The check valve includes a valve body defining a flow passage therethrough; a hinge shaft; a bushing coupled to the valve body and welded to the hinge shaft; and a closure element pivotally mounted on the hinge shaft for opening and closing the flow passage.

Description:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0001]    This invention was made with Government support under Contract Number N00019-02-C-3002 of the Joint Strike Fighter Program. The Government has certain rights in this invention 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention generally relates to check valves with flapper closure elements, and more particularly relates to methods and apparatus for retaining the hinge shaft on which the closure elements of check valves are pivotally mounted. 
       BACKGROUND 
       [0003]    Check valves with flapper (or “wafer”) type closure elements are utilized in many industries. The check valves are typically mounted in pipes or other such conduits enable fluid flow in one direction and prevent fluid flow in the opposite direction. The closure elements of the check valve are pivotally mounted on a hinge shaft and can be biased closed by a resilient element such as a hinge spring. The hinge shaft is typically mounted by press fitting the ends of the hinge shaft in through holes formed in a valve body. The valve body is then mounted in a pipe or conduit, for example, to enable air intake for an engine of an aircraft. 
         [0004]    Conventional check valves can encounter problems because the hinge shaft may loosen and migrate out of the valve body. This issue is exacerbated by the high temperature and vibration environments of many types of check valves, particularly where there is a clearance between the valve body and the walls of the conduit in which it is mounted. 
         [0005]    Accordingly, it is desirable to provide methods and apparatus for satisfactorily retaining hinge shafts in check valves. In addition, it is desirable to provide check valves that securely retain their hinge shafts in high temperature and vibration environments. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention. 
       BRIEF SUMMARY 
       [0006]    In accordance with one exemplary embodiment, a check valve includes a valve body defining a flow passage therethrough; a hinge shaft; a bushing coupled to the valve body and welded to the hinge shaft; and a closure element pivotally mounted on the hinge shaft for opening and closing the flow passage. 
         [0007]    In accordance with another exemplary embodiment, a method of retaining a hinge shaft in a check valve is provided. The method includes the steps of mounting a bushing on the hinge shaft; coupling the bushing to a valve body of the check valve; and welding the bushing to the hinge shaft to prevent movement of the hinge shaft in a longitudinal direction 
         [0008]    In accordance with yet another exemplary embodiment, a check valve includes a a valve body defining a flow passage therethrough; a hinge shaft; a bushing coupled to the valve body; a washer welded to the valve body and the hinge shaft; and a closure element pivotally mounted on the hinge shaft for opening and closing the flow passage 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein: 
           [0010]      FIG. 1  is an isometric view of a check valve in accordance with an exemplary embodiment; 
           [0011]      FIG. 2  is a cross-sectional view of the check valve of  FIG. 1  through line  2 - 2 ; 
           [0012]      FIG. 3  is a cross-sectional view of the check valve of  FIG. 1  through line  3 - 3 ; 
           [0013]      FIG. 4  is a more detailed view of a portion of  FIG. 3 ; 
           [0014]      FIG. 5  is a more detailed view of another portion of  FIG. 3 ; and 
           [0015]      FIG. 6  is an alternate embodiment of the portion shown in  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description. 
         [0017]      FIG. 1  is an isometric view of a check valve  100  in accordance with an exemplary embodiment. The check valve  100  includes a valve body  102  having an annular configuration defining a central flow passage  104 . The valve body  102  can be coupled to or within a pipe or conduit (not shown) to enable fluid flow into the pipe or conduit through the flow passage  104  in direction  105 . As will be discussed in further detail below, the check valve  100  is urged open by fluid flowing in the direction  105  while preventing fluid from flowing out of the check valve  100  in an opposite direction. 
         [0018]    The valve body  102  has an annular flange  106  that defines the flow passage  104  and that includes an upstream surface  108  and a downstream surface  110 . In one embodiment, the flow passage  104  is about 7 inches in diameter, although other sizes may be utilized depending on the specific application. The valve body  102  further includes a transverse post  112  that extends diametrically across the flow passage  104 . Generally, the transverse post  112  has an upstream surface  114  that is coplanar with the upstream surface  108  of the annular flange  106 . The valve body  102  also includes first and second flanges  116  and  118 , respectively, that extend perpendicularly to the plane of the annular flange  106 . 
         [0019]    As best shown in  FIG. 2 , which is a cross-sectional view of the check valve  100  of  FIG. 1  through line  2 - 2 , two generally flat valve closure elements  120  and  122  (also referred to as “flappers” or “wafers”), each shaped generally like one-half of a circular disc, are pivotally mounted on a hinge assembly  126 . The closure elements  120  and  122  are preferably identical, having flat and smooth upstream surfaces  128  and  130  and downstream surfaces  136  and  138 . In alternate embodiments, the closure elements  120  and  122  can be replaced by a greater or fewer number of closure elements, and/or the closure elements can have different shapes other than the semicircular shape in the depicted embodiment. 
         [0020]    As described in further detail below, the closure elements  120  and  122  are resiliently biased into a closed position in which the upstream surfaces  128  and  130  of the closure elements  120  and  122  come to a fluid-tight rest against the downstream surface  110  of the annular flange  106 , thus completely shutting off flow through the check valve  100 . When the closure elements  120  and  122  are in their fully open position, as illustrated by the dashed image  170  of  FIG. 2 , the closure elements  120  and  122  rest against a stop  172  mounted in between the first and second flanges  116  and  118  generally parallel and downstream to the transverse post  112  and the hinge assembly  126 . 
         [0021]    As best shown in  FIG. 3 , which is a cross-sectional view of the check valve  100  of  FIG. 1  through line  3 - 3 , the hinge assembly  126  includes a hinge shaft  127  having end portions  150  and  151  mounted and secured in holes  148  and  149  formed in the first and second flanges  116  and  118 . The hinge shaft  127  is generally cylindrical and has a circumferential surface  162 , although other configurations and cross-sectional shapes, such as square or hexagonal, can be provided. Generally, both holes  148  and  149  are through holes, although one or more of the holes  148  and  149  can be blind holes. The hinge shaft  127  extends across the flow passage  104 , generally parallel to the transverse post  112 . The mechanism for retaining the hinge shaft  127  in holes  148  and  149  of the flanges  116  and  118  is discussed in further detail below. 
         [0022]    The hinge assembly  126  includes helical spring  140  surrounding the hinge shaft  127 . The helical spring  140  includes two ends  132  and  134  that bear against the downstream surfaces  136  and  138  (not shown in  FIG. 3 ) of the closure elements  120  and  122  (not shown in  FIG. 3 ), respectively, to bias them into their closed position (such as shown in  FIG. 2 ). The force exerted by the helical spring  140  against the closure elements  120  and  122  is sufficient to hold them generally in the closed position, and to facilitate their automatic closure when fluid is not flowing through the valve, thereby preventing undesired reversed flow through the valve in the upstream direction. In an alternate embodiment, the helical spring  140  can be replaced by another resilient element, or omitted such that the valve is biased closed by gravity or air pressure. 
         [0023]      FIG. 4  illustrates circled portion  142  ( FIG. 3 ) of the check valve  100  in greater detail. Particularly,  FIG. 4  illustrates how the hinge shaft  127  is mounted and secured in the first flange  116 . The hinge assembly  126  further includes a bushing  190  that couples the hinge shaft  127  to the first flange  116  in hole  150 . The bushing  190  serves as a cylindrical lining for hole  150  and can be manufactured from the same or different material as the hinge shaft. The bushing  190  is configured as a blind hole with a bottom wall  191  that prevents the hinge shaft  127  from migrating out of the bushing  190 . The bushing  190  further includes a bushing flange  196  to support the bushing  190  in hole  150 . 
         [0024]      FIG. 5  illustrates circled portion  143  ( FIG. 3 ) of the check valve  100  in greater detail. Portion  143  is similar to portion  142  in that a bushing  192  couples the hinge shaft  127  to the second flange  118  in hole  149 . In this embodiment, the bushing  192  is configured as a through hole. The bushing  192  is welded to the hinge shaft  127  at or adjacent to position  198  to retain the hinge shaft  127  in the bushing  192 , and thus, in the valve body  102 . The bushing  192  may also include a bushing flange  197  to support the bushing  192  in hole  149 . 
         [0025]    The material to weld the hinge shaft  127  to the bushing  192  may include the same or similar material to the material utilized to form the hinge shaft  127  and/or bushing  192 , or a dissimilar material can also be used as filler material in the weld. The check valve  100  can be manufactured from any suitable metallic or non-metallic material, including plastics and ceramics. In one embodiment, the hinge shaft  127 , the bushing  192 , and the welding material include aluminum. Techniques for welding the hinge shaft  127  and the bushing  192  include fusion welding processes such as Gas Tungsten Arc Welding, Gas Metal Arc Welding, Laser Welding, and Electron-Beam Welding. 
         [0026]      FIG. 6  is an alternate embodiment of the portion  143  shown in  FIG. 5 . In  FIG. 6 , a bushing  182  can be, for example, manufactured from an unweldable material such as plastic ceramic. A retention component such as a washer  180  can be provided in a cavity  185  formed by the ends of the bushing  182  and the hinge shaft  127 , as well as the valve body  102 . The hinge shaft  127  can be welded to the washer  180 , such as at position  183 , and the valve body  102  can be welded to the washer  180 , such as at position  184 . Although  FIG. 6  illustrates the cavity  185 , other embodiments may omit the cavity  185 . As also shown in  FIG. 6 , a pin  186  can be provided between the bushing  182  and the hinge shaft  127  to prevent rotation of the hinge shaft  127  relative to the bushing  182 . 
         [0027]    In an alternate embodiment, the bushings  190  and  192  can be omitted, and the hinge shaft  127  may be welded directly to the valve body  102 . In yet another exemplary embodiment, a locking pin can be provided to engage one or more of the bushings  190  and  192  to assist the weld in retaining the hinge shaft  127 . In another alternative, the bushing  190  can be configured as a through hole and welded to the hinge shaft  127 . 
         [0028]    Embodiments of the check valve  100  enable the hinge shaft  127  to be retained without a substantial change to the weight and/or space requirements, particularly in high temperature and/or vibration environments. In one embodiment, the check valve  100  can withstand temperatures from about −40° F. to about 330° F. Although embodiments have been discussed in connection with check valves, these embodiment can also be utilized to a hinge shaft  127  in other types of valves. 
         [0029]    While at least one exemplary embodiment has been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention. It being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims.