Abstract:
The invention concerns a rapid connection coupling ( 10 ) for transferring high-pressure gases and/or liquid, in particular for refilling a high-pressure, mobile container such as a gas cylinder with oxygen in a home environment or at a transfill station with a transfill device. The coupling in question comprises the following elements: a tubular housing ( 11 ), an outer sliding sleeve ( 18 ) which can slide relative to the housing ( 11 ); a number of radially expanding collet chuck elements ( 15 ) mounted on the housing ( 11 ) and provided with an engaging contour ( 17 ) which facilitates connection to a matching connection fitting ( 30 ); and a sealing piston ( 22 ) capable of sliding centrally inside the housing ( 11 ), the said sealing piston being brought into contact with the connecting fitting ( 30 ). Internal parts (e.g., pin  25   b  and pin  25   c ) of the coupling are characterized by having a reduced or minimized volume, thereby reducing the volume of fluid expelled when removing the fitting ( 30 ) from the coupling ( 10 ), thereby reducing the intensity of sound created by disconnecting the fitting ( 30 ) from the coupling ( 10 ). Additionally, the coupling ( 10 ) is characterized by being easy to use and by having a relatively low parts count.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to and the benefit of U.S. Provisional Application Ser. No. 60/279,140, filed on Mar. 27, 2001. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to a rapid connection coupling for transferring gaseous and/or liquid fluids, especially for refilling a high-pressure, mobile container such as a gas cylinder with oxygen in a home environment. 
     BACKGROUND OF THE INVENTION 
     Rapid connection couplings for transferring gaseous and/or liquid fluids are known. Examples of such rapid connection couplings are shown and described in U.S. Pat. Nos. 5,927,683 and 5,575,510 and in EP-A 0 340 879 and WO-A 93/20378. 
     The known rapid connection couplings have a number of disadvantages making them unsuitable for use in refilling a high-pressure, mobile container (such as a gas cylinder) with oxygen in a home environment. The disadvantages of known rapid connection couplings include at least one or more of the following: (i) being relatively complicated to use, making them more suitable for use by a suitably trained cylinder refilling technician, (ii) allowing an unacceptably large amount of high-pressure gas to escape when the coupling is disengaged from a mating fitting affixed to the cylinder, creating an unacceptably loud sound, and possibly causing the fitting and cylinder to forcibly separate from the rapid connection coupling, creating the risk of a projectile hazard, and (iii) having a relatively high parts-count and an a correspondingly high relative cost to manufacture. 
     There is a need, therefore, for an improved rapid connection coupling for transferring gaseous and/or liquid fluids suitable for untrained users, especially for refilling a mobile container (such as a gas cylinder) with oxygen in a home environment. 
     SUMMARY OF THE INVENTION 
     The present invention is directed toward an improved rapid connection coupling. According to one aspect of the present invention, the improved rapid connection coupling of the present invention provides a coupling having a significantly reduce volume of escaping gas when disconnected from an associated fitting, which significantly reduces the intensity of the sound created by the disconnection process and reduces the risk of a projectile hazard. According to another aspect of the present invention, the improved rapid connection coupling is easy to use for untrained individual without a significant amount of hand strength or dexterity. According to yet another aspect of the present invention, there are no exposed pins or projections that might create a safety issue for the user. According to still another aspect of the present invention, surfaces exposed to damage by a user (wear points) are not used to create seals (the structures forming seals are internal to either the coupling or the fitting), thereby increasing the longevity of such a coupling in the field. 
     These and other advantages of the present invention will become more apparent from a detailed description of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the accompanying drawings, which are incorporated in and constitute a part of this specification, embodiments of the invention are illustrated, which, together with a general description of the invention given above, and the detailed description given below, serve to example the principles of this invention, wherein: 
         FIG. 1A  is a side plan view of a rapid connection coupling according to the present invention; 
         FIG. 1B  is an anterior plan view of a rapid connection coupling according to the present invention; 
         FIG. 1C  is a posterior plan view of a rapid connection coupling according to the present invention; 
         FIG. 2  is a one-quarter cross sectional view (with additional portions cut away) of a rapid connection coupling according to the present invention with a fitting according to the present invention partially inserted therein; 
         FIG. 3  is a one-quarter cross-sectional view (with additional portions cut away) of a rapid connection coupling according to the present invention fully connected to a fitting according to the present invention; 
         FIG. 4A  is a cross-sectional view of a rapid connection coupling and fitting according to the present invention taken along the line  4 — 4  in  FIG. 1B  in the fully connected position shown in  FIG. 3 ; 
         FIG. 4B  is a view showing an enlarged portion of  FIG. 4A ; 
         FIG. 5A  is a one-quarter cross-sectional view of a rapid connection fitting according to the present invention; 
         FIGS. 5B–5E  are perspective, top plan, side elevational, and front elevational views, respectively, of rapid connection fitting according to the present invention shown in  FIG. 5A ; 
         FIG. 6A  is a front elevational view of a sealing piston; 
         FIG. 6B  is a cross-sectional view of a sealing piston taken along the line  6 B— 6 B in  FIG. 6A ; 
         FIG. 7A  is a front elevational view of a coupling housing; 
         FIG. 7B  is a cross-sectional view of a coupling housing taken along the line  7 B— 7 B in  FIG. 7A ; 
         FIG. 8A  is a front elevational view of a first pin forming a mechanical check valve; 
         FIG. 8B  is a cross-sectional view of a first pin forming a mechanical check valve taken along the line  8 B— 8 B in  FIG. 8A ; 
         FIG. 8C  is a front elevational view of a first pin forming a mechanical check valve; 
         FIG. 9A  is a front elevational view of a second pin forming a mechanical check valve; 
         FIG. 9B  is a cross-sectional view of a second pin forming a mechanical check valve taken along the line  9 B— 9 B in  FIG. 9A ; 
         FIG. 9C  is a front elevational view of a second pin forming a mechanical check valve; 
         FIG. 10A  is a front elevational view of a housing insert; 
         FIG. 10B  is a cross-sectional view of a housing insert taken along the line  10 B— 10 B in  FIG. 10A ; 
         FIG. 11A  is a front elevational view of an annular brass seat; 
         FIG. 11B  is a cross-sectional view of an annular brass seat taken along the line  11 B— 11 B in  FIG. 11A ; and 
         FIGS. 12 and 13  show fittings according to the present invention that can be used to permit and prevent certain cross-uses, as shown in  FIGS. 14–16 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A preferred embodiment of a rapid connection coupling  10  and fitting  30  according to the present invention is shown in  FIGS. 1A–16 .  FIGS. 1A ,  1 B, and  1 C show the rapid connection coupling  10  in plan view without an associated fitting.  FIG. 2  shows the rapid connection coupling  10  shortly before the connection to a connection fitting  30 . The rapid connection coupling  10  comprises a tubular housing  11 , where the right end here serves as the inlet  12  and the left end as the outlet  13  for feeding on the transferred fluid to the connection receptacle, such as a nipple or other fitting  30 . 
     On the outlet  13  end, there are provided several jaws  15  arranged in tubular form and which are radially spread in the position shown in  FIG. 2  shortly before plugging on to the connection fitting  30 , as is also shown in the previously recited WO-A 93/20378 for example. The elongated jaws  15 , of which there are preferably at least three, and more preferably between three and six, and most preferably four, are arranged around the housing  11  and are hooked in an annular groove  11   a  of the housing  11  at their ends here on the right and are biased by an annular spring (e.g., an O-ring)  16  so that the jaws  15  are radially spread. At the end here to the left, on the inwardly offset surface, the jaws  15  each have an interlocking engagement profile  17  formed in correspondence with the connection profile  31  of the connection fitting  30 . For example, in the specific implementation shown in the figures, the fitting  30  has a cylindrical portion  31   a  and a flared portion  31   b  (i.e., a frustum of a cone) flaring from the cylindrical portion  31   a  and the jaws  15  form an engagement profile having a cylindrical portion  17   a  and a flaring portion  17   b  flaring from the cylindrical portion  17   a , so that when interlocked the cylindrical portions  17   a  and  31   a  oppose and engage each other and the flaring portions  17   b  and  30   b  oppose and engage each other. 
     Connection fitting  30  preferably also comprises a housing  33  having a threaded portion  32  and a pneumatic check valve  34 . Check valve  34  is preferably a ball and spring type check valve. More specific to the figures, check valve  34  preferably comprises a ball  34   a  biased by a spring  34   b  toward a seat surface  34   c  of an insert  34   d  inside housing  33 . Spring  34   b  is guided and centered by a centering insert  34   e  inside housing  33 . Ball  34   a  is urged against first and second O-rings  34   f ,  34   g , which form a seal with ball  34   a . Connection fitting  30  preferably also comprises an inlet bore  35 , which is formed by a bore  35   a  in housing  33  and a bore  35   b  in insert  34   d  and accepts a second pin of the coupling  10 , discussed below. In a middle portion of bore  35 , an o-ring  36   a  and backup ring  36   b  form a seal  36  with the second pin of coupling  10 , discussed below. The fitting  30  also preferably includes a filter  37 . The foregoing pieces are held inside housing  33  by a retaining ring (snap ring)  38 . 
     An outer sliding sleeve  18  is provided around the jaws  15  and is guided on the cylindrical outer surface  11   b  of the housing  11  and is biased by a relatively weak compression spring  19  in the direction of the connection fitting  30 . The compression spring  19  abuts the housing  11  via an abutment ring  20  and a retaining ring (snap ring)  21 . 
     A sealing piston  22  is guided on the peripheral surface  11   c  of the housing  11  disposed towards the outlet  13  and preferably comprises an annular flange  22   b  for engagement with the front face  39  of fitting  30 . 
     Furthermore, there is a check valve  25  fitted centrally in the housing  11 . Check valve  25  is sealed relative to a sealing surface  27  on the housing  11  by means of a first seal  26 , preferably comprising sealing ring  26   a  cooperating with a special hard seat seal  26   b , in the closed position shown in  FIG. 4B . The check valve  25  is biased by a compression spring  28 , which is guided and centered by a centering insert  29  in the housing  11  and abuts the latter. Through this check valve  25  it is ensured that the fluid fed through the housing  11  cannot flow out even with the connecting valve on the refill cylinder or the like open in the uncoupled position or just before the connection of the rapid connection coupling  10  to the connection fitting  30 , as shown here in  FIG. 2 . 
     The check valve  25  has a centrally arranged first pin  25   b  and a centrally arranged second pin  25   c , both of which slide along the longitudinal axis of the housing  11 . First pin  25   b  functions as a valve plunger and has a conical sealing surface  25   a  that engages seal  26 . Second pin  25   c  is centered and sealed with respect to housing  11  by a second seal  26 ′, preferably comprising sealing ring  26   c  cooperating with a backup ring  26   d  (essentially a plastic washer). (Using the seal  26 ′ as described above will allow a coupling  10  according to the present invention to maintain a high pressure, e.g., 2000 psi, for an extended period of time. In the alternative, seal  26 ′ can be replaced with a metal against metal seal, which will provide a substantial enough seal to allow the coupling  10  and fitting to pressurize a cylinder, e.g., an oxygen cylinder, to 2000 psi or greater, but will also allow the high pressure to slowly leak down to about 100 psi once any compression upstream of the coupling  10  has stopped. Allowing the high pressure to slowly bleed off through the coupling  10  after compression has ceased makes the already easy to operate coupling  10  even easier to use because the user need not overcome the high pressure to use the coupling  10  next time.) A separate stepped, annular brass seat  26   e  cooperates with housing  11  and seals  26 ,  26 ′. First pin  25   b  preferably includes a very narrow fluid passage therein, which preferably comprises a central bore  25   d  in fluid connection with at least one radial bore  25   e , positioned so the radial bore  25   e  is completely sealed by seal  26  in the closed position shown in  FIG. 4B . Second pin  25   c  also preferably includes a very narrow fluid passage therein, which is preferably in fluid communication with the fluid passage of first pin  25   b . This passage in second pin  25   c  preferably comprises a central bore  25   f  positioned to be in fluid communication with central bore  25   d  of first pin  25   b . The second pin  25   c  preferably includes an integral guide ring  25   g  cooperating with a surface  11   e  of housing  11 . The second pin is retained in housing  11  by an abutment ring  42  (essentially a brass washer) held in place by a retaining ring (snap ring)  43 . First pin  25   b  preferably includes a narrowed stem portion  25   h  that serves to guide first pin  25   b  with respect to seal  26  and seat  26   e . The coupling  10  also preferably comprises a filter  44  in the fluid flow. The first pin  25   b , seal  26 , seal  26 ′, seat  26   e , spring  28 , centering insert  29 , and filter  44  are retained in housing  11  by a retaining ring (snap ring)  45 . A stop  29   a  of the centering insert  29  limits the axial stroke of the first pin  25   b  of check valve  25 . A stop  1  if of the housing  11  limits the axial stroke of the second pin  25   c  of check valve  25 . 
     Sealing piston  22  is biased by a compression spring  41 , which abuts a shoulder  11   d  of the housing  11  on one side and a shoulder  22   a  of the sealing piston on the other side. As can be seen from  FIG. 2 , sealing piston  22  has an annular projection  22   c  facing towards the outlet  13  that while in the open position engages an inwardly offset region  15   a  of the jaws  15 , whereby they are held in their radially spread, open position. The sealing piston  22  is urged by the compression spring  41  toward the fitting  30  until the projection  22   c  abuts against the inwardly offset region  15   a  of the jaws  15 , which stops the movement of sealing piston  22 . 
     The connected position of the rapid connection coupling and the fitting  30  is shown in  FIG. 3 . On plugging the rapid connection coupling  10  on to the connection fitting  30 , tip  25   j  of second pin  25   c  is inserted into the bore  35  of fitting  30  and serves to align and guide fitting  30  with respect to the coupling  10 . As the fitting  30  is further inserted into coupling  10 , surface  25   k  of second pin  25   c  engages front surface  39  of fitting  30  and the very tip  25   m  of second pin may also engage ledge  34   h  of insert  34   d . Thus further movement of fitting  30  into coupling  10  causes second pin  25   c  to move toward first pin  25   b . Second pin  25   c  cooperates with stem  25   h  of first pin  25   b , thereby sliding first pin  25   b  toward the inlet end  12 , thereby exposing radial bore  25   e  from seal  26 , the thereby opening mechanical check valve  25 . As the second pin  25   c  is inserted into bore  35  of fitting  30 , tip  25   j  engages O-ring  36   a  of fitting  30 , thereby forming a seal to prevent escape of fluid. After a small movement (e.g., a few millimeters) of the sealing piston  22  to the right, the inner surfaces  15   a  of the jaws  15  bearing on the projection  22   c  of sliding piston  22  are freed from their blocked position, so that they can snap inwardly, so that the engagement profile  17  can engage with the correspondingly formed connection profile  31  of the connection fitting  30 . Practically simultaneously, the sliding sleeve  18  becomes free for axial movement to the left, since the sliding sleeve  18  is biased by the compression spring  19 . By virtue of its axial movement, inner surface  18   a  of the sliding sleeve  18  engages over the outer ends  15   b  of the jaws  15 , so that they are retained interlocked in their engaged position on the connection fitting  30 . 
     In order to release the rapid connection coupling  10  and thus return to the open position of  FIG. 2  from the attached position of  FIG. 3 , the sliding sleeve  18  is manually retracted. To facilitate this, preferably, the sliding sleeve has a projection, e.g., an integral annular flange  18   c , extending therefrom, to provide a gripping region. In addition, or in the alternative, the outer surface of sliding sleeve  18  can be provided with knurling or other suitable profiling of the outer surface. After a short movement of the sliding sleeve  18  the jaws  15  can again spread radially, whereby the sealing piston  22  is simultaneously displaced to the left towards the outlet end  13  under the action of the compression spring  41  back into the position of  FIG. 2 . The jaws  15  are only closed when the sealing contact between the tip  25   j  of second pin  25   c  and the sealing ring  32  of fitting  30  is ensured, since the open position of the jaws  15  is maintained until the closed position of the jaws  15  is enabled by the axial displacement of the sealing piston  22  to produce the connection practically at a stroke. 
     One advantage of the present invention is that the components of coupling  10  were configured to significantly reduce the volume of fluid released when the coupling  10  releases the fitting  30 . This was accomplished by (i) significantly reducing the volume of fluid that will necessarily be released when the coupling  10  releases the fitting  30  and (ii) decreasing the required travel of parts before the flow of fluid is stopped. More specific to the implementation shown in the figures, the volume of fluid released when the coupling  10  releases the fitting  30  is reduced by (i) significantly reducing the volume of the bores within the check valve  25  downstream of seat  26  and (ii) significantly reducing the travel distance of parts required for check valve  25  to stop the flow of fluid. 
     As to reduced volume of fluid released, the bore  25   d  of first pin  25   b  is about 1 mm (about 0.375 inches) in diameter and is about 5.5 mm (about 0.210 inches) deep. The radial bore  25   e  of first pin  25   b  is about 1 mm (about 0.0375 inches) in diameter and about 1.5 mm (about 0.0575 inches) deep. Therefore, the fixed volume of fluid that will escape from first pin  25   b  when coupling  10  releases fitting  30  is about 5.5 mm 3  (about 0.0003 cubic inches). Similarly, the bore  25   f  of second pin  25   c  is about 1 mm (about 0.0375 inches) in diameter and is about 28.5 mm (about 1.125 inches) deep. Therefore, the fixed volume of fluid that will escape from second pin  25   c  when coupling  10  releases fitting  30  is about 22 mm 3  (about 0.0012 cubic inches). Also, the fact that tip  25   j  of second pin  25   c  is inserted into bore  35  of fitting  30  allows additional expelled fluid volume to be reduced, because that tip  25   j  fills a significant volume inside bore  35  that might otherwise be filled with high-pressure fluid. 
     As to reduced amount of travel required for check valve  25  to stop the flow of fluid through first pin  25   b , when in use, the radial bore(s)  25   e  are displaced from seal  26  in the range of from about 0 mm to about 13 mm, preferably by only about 6.5 mm. Thus, when fitting  30  is released, the first pin  25   b  need only move within that range or that distance to seat, thereby stopping the flow of fluid through first pin  25   b.    
     Although the improved rapid connection coupling and fitting according to the present invention can be used in virtually any fluid transfer application, because of their relative ease of use and relatively quiet connection and disconnection the improved rapid connection coupling and fitting according to the present invention have particular utility in the application of filling mobile oxygen containers, e.g., with home-based oxygen cylinder fillers in the home environment and with transfill devices at dealers, etc. The connection and fitting are particularly suited to oxygen refilling in the home environment and can be incorporated in the home oxygen refilling systems taught by Invacare U.S. Pat. No. 5,988,165 and in copending Invacare U.S. patent application Ser. Nos. 09/154,442 (filed on Sep. 16, 1998), and Ser. No. 09/695,612 (filed on Oct. 24, 2000), all of which are hereby incorporated by reference. In the aforementioned patent and both applications, the coupling  10  of the present invention would be used between the compressor  100  and the cylinder  500 , with the coupling  10  being in fluid connection downstream of the compressor and the fitting  30  being preferably incorporated into the cylinder  500  to facilitate the rapid and easy connection and disconnection of the cylinder  500  with respect to the coupling  10 . Additionally, in the later application, the coupling  10  of the present invention can also replace the fill connector  845  in the unit shown in  FIG. 13  and described in that application. 
     Those skilled in the art will appreciate which materials will be suitable and/or required for the particular coupling application in mind for the coupling  10  and fitting  30  according to the present invention. For example, for the high-pressure oxygen application, brass, stainless steel, PTFE, EDPM, POM, and Gleitmo 595 lubrication are all acceptable for parts coming into contact with the oxygen. Thus, in the coupling  10  and fitting  30  for use with high-pressure oxygen, the O-rings ( 16 ,  26   a ,  26   c ,  34   f ,  34   g , and  36   a ) are preferably made of EPDM, the backup rings ( 26   d  and  36   b ) are preferably made of PTFE, part  26   b  (L-shape in cross section) is preferably made of POM, the springs and retaining rings (snap rings) contacting the oxygen ( 43 ,  45 , and  38 ) are preferably made of 301 or 302 stainless steel, retaining ring (snap ring)  21  is preferably made of coated stainless steel, sleeve  18  is preferably made of an aluminum alloy (0.8% silicium, 0.8% iron, 0.5–1% manganese, 0.4–1.8% magnesium, 0.1% chromium, 0.8% zinc, 0.3% others together, and the rest being aluminum), and the remaining metal pieces ( 11 ,  15 ,  22 ,  20 ,  29 ,  25   b ,  25   c ,  26   e ,  33 ,  34   e , and  34   d ) are preferably made of brass (57–59% copper, 2.5%–3.5% lead, 0.1% aluminum, 0.5% iron, 0.5% nickel, 0.4% tin, 0.2% others together, with the rest being zinc). 
     As discussed above, the connection fittings  30  according to the present invention preferably include a cylindrical portion  31   a .  FIGS. 12 and 13  show two fittings having cylindrical portions  31   a  of different lengths, corresponding to two different pressures. Fitting  30  can, for example, be designated to be a lower pressure fitting, e.g., 2000 psi, and fitting  30 ′ can, for example, be designated to be a higher pressure fitting, e.g., 3000 psi. Similarly by varying the length of the corresponding portion of jaws  15 , as shown in FIGS.  3  and  14 – 16 , it is possible to designate a low pressure coupling  10  and a high pressure coupling  10 ′. Thus, one can designate a low-pressure fitting  30  (i.e., a low pressure cylinder) that will function with a low pressure coupling  10  ( FIG. 3 ) but will not function with a high pressure coupling  10 ′ because of physical interference between a structure  50  and the jaws  15  (see  FIG. 16 ), thereby preventing a cylinder rated for only 2000 psi from being used with a coupling capable of pressurizing that cylinder to 3000 psi. Similarly, it is possible to designate a high-pressure fitting  30 ′ (i.e., a high-pressure cylinder) that will function with a low pressure coupling  10  ( FIG. 15 ) and will also function with a high pressure coupling  10 ′ (see  FIG. 14 ). This type of differentiation system (varied lengths of cylindrical portions  31   a  and corresponding jaw portions  15 ), can also be used to differentiate couplings  10  and fittings  30  based on other criteria, e.g., different gases, etc. 
     While the present invention has been illustrated by the description of embodiments thereof, and while the embodiments have been described in some detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicant&#39;s general inventive concept.