Patent 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 coupling the hinge shaft to the valve body; a pin secured to the valve body and engaging the bushing; and a closure element pivotally mounted on the hinge shaft for opening and closing the flow passage.

Full Description:
[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 satisfactory 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 coupling the hinge shaft to the valve body; a pin secured to the valve body and engaging the bushing; 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 to couple the hinge shaft to a valve body of the check valve; inserting a pin in a groove of the bushing; and securing the pin to a valve body of the check valve to prevent movement of the bushing and the hinge shaft in a longitudinal direction. 
         [0008]    In accordance with yet another exemplary embodiment, a check valve includes a valve body comprising a flow passage and a bore; a hinge shaft; a bushing having a circumferential surface and coupling the hinge shaft to the valve body; a pin at least partially housed in the valve body and engaging the bushing at the circumferential surface to prevent movement of the bushing and the hinge shaft in a longitudinal direction; 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 ; and 
           [0014]      FIG. 5  is a more detailed view of another portion of  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    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. 
         [0016]      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. 
         [0017]    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 . 
         [0018]    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. 
         [0019]    As described in further detail below, the closure elements  120  and  122  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 . 
         [0020]    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. 
         [0021]    The hinge assembly  126  may include a 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. 
         [0022]      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. 
         [0023]    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  includes a groove  152  formed in its circumferential surface. The groove  152  is configured to receive a locking pin  154  inserted through a bore  156  in the valve body  102  that is aligned with the groove  152 . The locking pin  154  is generally inserted at approximately 90° to a longitudinal axis  160  of the hinge shaft  127  and the bushing  190 , although any angle between 45° and 135°, and preferably 80° and 100°, can be provided. The locking pin  154  prevents the bushing  190  (and thus, the hinge shaft  127 ) from moving along the longitudinal axis  160 , thus preventing the hinge assembly  126  locking pin from migrating out of the hole  148  and out of the valve body  102 . The locking pin  154  is securely retained in the bore  156  by threads formed on the locking pin  154  that cooperate with thread formed within the bore, i.e., a threaded screw attachment between the locking pin  154  and the bore  156 . 
         [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 . The bushing  192  is configured as a blind hole with a bottom wall  193  that prevents the hinge shaft  127  from migrating out of the bushing  192 . The bushing  192  includes a groove  153  formed in its circumferential surface. The groove  153  is configured to receive a second locking pin  155  inserted through a bore  157  in the valve body  102  that is aligned with the groove  153 . The locking pin  155  is generally inserted at approximately 90° to a longitudinal axis  160  of the hinge shaft  127  and the bushing  191 , although any angle between 45° and 135°, and preferably 80° and 100°, can be provided. The locking pin  155  prevents the bushing  191  (and thus, the hinge shaft  127 ) from moving along the longitudinal axis  160 , thus preventing the hinge assembly  126  from migrating out of the hole  148  and out of the valve body  102 . The locking pin  155  is securely retained in the bore  157  by threads formed on the locking pin  155  that cooperate with thread formed within the bore  157 . 
         [0025]    In an alternate embodiment, the grooves  152  and  153  on the bushings  190  and  192  replaced by a slot or hole. In another embodiment, locking pin  155  can be omitted and the hinge assembly  126  can be retained by the single locking pin  154 . Moreover, in yet another alternate embodiment, one or more of the bushings  190  and  192  can be welded to the hinge shaft  127 . 
         [0026]    The locking pins  154  and  155  and the bushings  190  and  192  enable the hinge shaft  127  to be retained without a substantial change to the weight and/or space requirements of the check valve  100 . Moreover, the locking pins  154  and  155  and the bushings  190  and  192  retain the hinge shaft  127  in high temperature and/or vibration environments. The check valve  100  can be manufactured from any suitable metallic or non-metallic material, including plastics and ceramics. In one embodiment, the valve body  102 , the closure elements  120  and  122 , bushings  190  and  192 , and the hinge shaft  127  can be manufactured from aluminum, and the locking pins  154  and  155  can be manufactured from stainless steel. Generally, the check valve  100  is manufactured to withstand temperatures from about −40° F. to about 330° F. Although embodiments have been discussed in connection with check valves, the locking pins  154  and  155  and the bushings  190  and  192  can retain a hinge shaft  127  in other types of valves. 
         [0027]    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.

Technology Classification (CPC): 8