Abstract:
A fitting connector for a pressure vessel including a bushing for mounting within an aperture defined in a pressure vessel wall. The bushing includes a cylindrical bushing body having a head portion at one end thereof and including at least a pair of locking members for engaging along an interior surface of the pressure vessel wall. The locking members are provided with a contoured surface for engaging with detent members formed on the interior of the pressure vessel wall whereby the bushing is positively locked in a predetermined rotational orientation on the pressure vessel wall and is retained in place until a predetermined torque force is applied.

Description:
REFERENCE TO PROVISIONAL APPLICATION 
   This application claims benefit of the filing date of U.S. Provisional Application No. 60/374,731 filed Apr. 23, 2002. 

   BACKGROUND OF THE INVENTION 
   The present invention relates to a fitting for use with air tanks and, more particularly, to a fitting including a twist end bushing for interfacing with an opening in an air tank. 
   Air tanks are typically provided with fittings for connection to tubing or other passageways leading to the air tank. In the past, such fittings have been attached to the air tank by means of a bushing welded to an aperture formed through the wall of the tank. Accordingly, production of the tank requires attention to proper formation of the weld connection and a corresponding labor and manufacturing time cost associated with this operation. 
   Accordingly, there is a need for a fitting structure for use with air tanks wherein the fitting structure is easily assembled to the tank. In addition, there is a need for such a fitting structure wherein the fitting structure provides a reliable seal with the tank. 
   SUMMARY OF THE INVENTION 
   A fitting connection is provided for use with a pressure vessel wherein the fitting connection includes a bushing having a cylindrical bushing body and a head portion located at an upper end of the bushing body. The bushing body is inserted through an aperture in a pressure vessel wall to form an interface between the pressure vessel wall and a fitting, such as a fitting for an air tube leading from the pressure vessel. 
   In one embodiment, a pair of diametrically opposed locking members are located on the bushing body in spaced relation to the head portion to define a groove between a lower surface of the head portion and an upper surface of the locking members for receiving edge portions of the vessel wall defining the aperture. In addition, an upper surface of each locking member is contoured to increase frictional engagement and provide a resistance to turning of the bushing body when it is mounted to the pressure vessel in order to insure that a predetermined torque force is required to remove or loosen the bushing from the pressure vessel. The contoured surface includes a recess for receiving a detent formed on an interior surface of the pressure vessel wall. 
   The locking members are further formed with catch elements extending parallel to a longitudinal axis of the bushing body and located in spaced relation to the bushing body. The catch elements include a tang element at a distal end thereof for preventing withdrawal of the bushing body from the aperture. 
   In a second embodiment, the bushing body has four equally spaced locking members, which have contoured surfaces with recesses to receive the four equally spaced detents on the interior surface of the pressure vessel wall. 
   Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a bottom perspective view of the bushing for the fitting connector of the present invention; 
       FIG. 2  is a side elevational view of the bushing of  FIG. 1 ; 
       FIG. 3  is a cross-sectional view taken along the line  3 — 3  of FIG.  2  through the center of the bushing and passing through the locking members; 
       FIG. 4  is a top perspective view of an end wall for a pressure vessel configured for use with the bushing of the present invention; 
       FIG. 5  is an interior plan view thereof; 
       FIG. 6  is a cross-sectional view taken along line  6 — 6  in  FIG. 5 ; 
       FIG. 7  is a cross-sectional view taken through the assembled bushing and pressure vessel wall; 
       FIG. 8  is a bottom perspective view of a second embodiment of the bushing for the fitting connector of the present invention; 
       FIG. 9  is a side elevational view of the bushing of  FIG. 8 ; 
       FIG. 10  is a bottom plan view of the bushing of  FIG. 8 ; and 
       FIG. 11  is an interior plan view of an embodiment of an end wall for a pressure vessel configured for use with the bushing of FIG.  8 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIGS. 1-3 , the fitting structure of the present invention includes a bushing  10  for mounting to the wall of a tank and for supporting a fitting, illustrated diagrammatically as  12 . The bushing includes a cylindrical body  14  defined by a cylindrical outer surface  16  and a cylindrical inner surface  18  wherein the cylindrical inner surface  18  defines a cylindrical aperture through the bushing  10 . 
   A head portion  20  is formed integrally with and extends radially outwardly from the cylindrical body  14 . The head portion  20  defines a tool-engaging portion of the bushing  10  and in the illustrated embodiment is provided with a hexagonal shape for engagement with a wrench. 
   A pair of locking members  22 ,  24  are located on diametrically opposite sides of the cylindrical body  14 . Each locking member  22 ,  24  includes a base portion  25  extending radially from the outer surface  16  of the cylindrical body  14  and includes an upper surface  26  facing toward a lower surface  28  of the head portion  20 . 
   Each locking member  22 ,  24  further includes a catch element  30  extending downwardly from the base portion  25  parallel to a longitudinal axis  13  of the body  14  and in spaced relation to the outer surface  16  of the cylindrical body  14 . The catch elements  30  each include a pair of tangs  32 , which are separated by a notch or groove  130 . 
   The upper surface  26  of the base portion  25  includes an end wall  34  at one end thereof, and the surface  26  at an opposite end  36  is inclined or ramped slightly upwardly in a direction toward the end wall  34  (see FIG.  2 ). Further, the upper surface  26  includes a recessed portion  38  intermediate the ends of the upper surface  26 . 
   Referring to  FIGS. 4-6 , an end wall  40  for an air tank is illustrated and includes an aperture  42  having a diameter closely matching the diameter of the outer surface  16  of the cylindrical body  14 . A pair of slots  44 ,  46  are defined on diametrically opposite sides of the aperture  42  and are formed with a length in a circumferential direction, which corresponds to the circumferential length of the catch elements  30 . 
   In addition, a protruding detent element  48 ,  50  is located adjacent to each of the slots  44 ,  46  on an interior surface  52  of the end wall  40 , as may be best seen in  FIGS. 5 and 6 . 
   It should be noted that the end wall  40  is generally formed with a dome shape. However, the area directly surrounding the aperture  42  is formed as a circular flattened area to define a generally flat annulus area  54 . 
   Referring further to  FIG. 7 , the bushing  10  is assembled to the end wall  40  by inserting the bushing  10  with the locking elements  22 ,  24  passing through the slots  44 ,  46 . It should be noted that as the locking members  22 ,  24  pass through the slots  44 ,  46 , the tangs  32  will cause the catch elements  30  to flex inwardly, and further will prevent removal of the bushing  10  from the aperture  42  without application of an inward force on the catch elements  30 . 
   With the bushing  10  fully inserted through the aperture  42 , a groove area  56  (see  FIG. 3 ) defined between the upper surface  26  of the locking members  22 ,  24  and the lower surface  28  of the head portion  20  will be aligned with an edge of the end wall  40 . Rotation of the bushing  10  in a clockwise direction will cause the edge of the end wall  40  to pass into the grooves  56 . Further, during rotation, the detents  48 ,  50  will ride along the inclined portions  36  until they engage within the recesses  38  in a stop position. The end walls  34  are located to engage edges of the slots  44 ,  46  to prevent over-rotation of the bushing  10 . 
   It should be noted that rotation of the bushing  10  results in the detents  48 ,  50  progressively biasing the head portion  20  into engagement with the upper surface of the end wall  40 , and that engagement of the detents  48 ,  50  within respective recesses  38  provides a predetermined frictional engagement between the bushing  10  and the end wall  40  which requires a predetermined torque force to remove the bushing  10  through counterclockwise rotation. Further, the downward force applied against the head portion  20  results in a sealing force applied against an O-ring  58  located within a groove  60  in the lower surface  28  of the head portion  20 . Also, to further facilitate sealing of the head portion  20  against the upper surface of the end wall  40 , the upper surface of the end wall  40  is provided with a powder coating to insure a very smooth sealing surface between the O-ring  58  and the end wall  40 . 
   When air pressure is present interiorly of the end wall  40 , such as air pressure present within an air tank, the bushing  10  will be biased outwardly, thus increasing the frictional pressure at the engagement between the upper surfaces  26  of the locking members  22 ,  24  and the detents  48 ,  50 . This additional pressure and frictional force insures that the bushing  10  is prevented from being rotated out of engagement with the end wall  40  when an air pressure is present within the tank. 
     FIGS. 8-11  show a second embodiment of the bushing generally indicated at  10 ′ for insertion in an end wall  40 ′, which has slots  44  and  46  and additional slots  144  and  146 . The four slots  44 ,  46 ,  144  and  146  are equally spaced around the opening or aperture  42 ′. The end wall  40 ′ has the two detents  48  and  50  along with additional detents  148  and  150 , so that the four detents are equally spaced around the aperture  42 ′. The bushing  10 ′ has four equally spaced locking members  22 ′,  122 ,  24 ′ and  124 , whose structure is the same as members  22  and  24 , except the catch element  30 ′ of each member does not have the ramped or inclined surface  36  and does not have the groove or notch  130  of the embodiment of  FIGS. 1-3  and, thus, each locking member  22 ′,  122 ,  24 ′ and  124  has a continuous tang  32 ′. However, each of the elements  30 ′ could be further modified to have an inclined or ramped surface at the open end of the groove  56 ′. 
   The bushing  10 ′ is assembled in the end wall  40 ′ in the same manner as the bushing  10  in the end wall  40 . The only difference is that the bushing  10 ′ has four locking members  22 ′,  122 ,  24 ′ and  124 , each with a depression or recessed portion  38  instead of just two locking members  22  and  24 . 
   While the form of apparatus herein described constitutes a preferred embodiments of this invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.