Abstract:
A coupling having a housing with an internal bore sized to receive a tube therein, a spacer bushing non-movably retained against axial movement within the bore, and first and second gripper rings each having a peripheral portion non-movably retained against axial movement within the bore prior to and during operation of the coupling with the tube therein with teeth protruding inwardly into the bore sufficient to engage the tube. The gripper teeth being non-retractable, and the gripper rings and spacer bushing being held tightly together within the housing. The coupling may include a seal for application of pressurized fluid to the tube.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of U.S. Ser. No. 11/764,712 filed Jun. 18, 2007, and issued Apr. 28, 2009 as U.S Pat. No. 7,523,966, which is a continuation of U.S. Ser. No. 11/061,139 filed Feb. 18, 2005 and issued Jun. 19, 2007 as U.S. Pat. No. 7,232,159, which is a continuation of U.S. Ser. No. 10/266,935 filed Oct. 7, 2002 and issued Mar. 1, 2005 as U.S. Pat. No. 6,860,523, which is a continuation of U.S. Ser. No. 09/570,846 filed May 12, 2000 and issued Oct. 15, 2002 as U.S. Pat. No. 6,464,266, which is a continuation-in-part of U.S. Ser. No. 09/425,909 filed Oct. 21, 1999 (now abandoned) and a continuation-in-part of U.S. Ser. No. 09/216,376 filed Dec. 18, 1998 (now abandoned), and claims the benefit of PCT/US99/30149, filed Dec. 17, 1999, which applications are incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     This invention pertains to removable couplings of the type for securing a plastic or copper tube by pressing on the tube without the need for welding or solder. 
     BACKGROUND OF THE INVENTION 
     U.S. Pat. No. 4,911,406 shows a tube coupling in which a metal or plastic tube can be coupled in a fluid-tight connection to a valve or the like simply by pressing the tube into the coupling. The tube is held into the coupling by a flexible gripper ring having teeth, which bite into the tube to prevent the tube from being pushed out by the fluid pressure in the coupling. The teeth are arranged such that the tube can be removed from the coupling by unscrewing the coupling but cannot be removed simply by axially pulling the tube without rotation of the tube. An O-ring seal is provided to prevent leakage of fluid outside of the coupling around the tube. 
     One of the advantages of the invention of the U.S. Pat. No. 4,911,406 is that by screwing the tube out of the gripper ring there is minimal damage to the surface of the tube. This then enables other advantageous arrangements of the seal and the gripper ring within the coupling. With the introduction of softer plastic tubing, such as, polybutylene or PEX (cross-linked polyethylene, plastic) to the plumbing industry, the demands on the holding power of the gripper ring have increased. The softer tubing material can cause the teeth of the gripper ring to gouge grooves in the tubing when the tubing is subjected to high numbers of repeated cycles at higher hydrostatic pressures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an axial section of the coupling embodying the principles of the invention. 
         FIG. 2  is an exploded view of the coupling shown in  FIG. 1 . 
         FIG. 3  is a fragmentary section of the gripper ring showing one of the gripper teeth. 
         FIG. 4  is a generic illustration of what could be a test cap or a valve or other coupling device product embodying the principles of the invention. 
         FIG. 5  shows the O-ring seal and gripper ring arrangement of this invention within the valve of the type shown in U.S. Pat. No. 4,911,406. 
         FIG. 6  is an axial section of the coupling embodying the principles of the invention with multiple gripper rings for use, for example, with a valve. 
         FIG. 7  is an exploded view of the coupling shown in  FIG. 6 . 
         FIG. 8  is a fragmentary section of the gripper ring showing one of the gripper teeth. 
         FIG. 9  is a generic illustration of uses for the coupling with what could be a valve, a shower head, a tub faucet coupling, a tube coupling, or any other application or use for this unique coupling. 
         FIG. 10  shows another embodiment of the invention with three gripper rings. This view is intended to show that the number of gripper rings can be any multiple of two or more. 
         FIG. 11  shows still another embodiment of the coupling used for a test cap. These various views are intended to show that the coupling has a wide variety of uses and configurations not all of which are shown for purposes of brevity. 
         FIG. 12  shows another embodiment of the coupling. 
         FIG. 13  shows another embodiment in which a valve using the push-on invention is used to replace a conventional metal valve with its normal compression ring. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     One improvement described herein is the reverse position of a gripper ring in the coupling from the position shown in the U.S. Pat. No. 4,911,406. In the illustrated embodiments with this improvement, the seal, such as an O-ring seal, is arranged axially inward of the gripper ring in the outer housing of the coupling. This is followed by a spacer bushing which holds the ring in place and the gripper ring, with its teeth, is on the axially outer side of the spacer bushing. This enables the detection of a leak caused by inadequately inserting a tube into the O-ring seal. It is particularly advantageous also in the situation of re-piping or replacing a previous metal valve to enable the existing compression ring used with metal vales to fit into a valve using this gripper ring arrangement. 
     Another improvement described herein over U.S. Pat. No. 4,911,406 is the provision of two or more gripper rings for increasing the holding power of the rings in the coupling for use with the softer tubing. The two or more gripper rings co-act on the tubing in a synergistic effect distributing the load between them to substantially increase the holding power of the rings in the softer tubing. It is believed that the softness of the tubing allows movement of the teeth in the plastic until the load on the rings is distributed over more of the rings thus increasing the ultimate holding power of the rings. 
     Other embodiments are illustrated and described herein. 
     As best shown in  FIG. 1 , the unique coupling is shown in one form as a generic coupling but could be a test cap. A test cap, for example, is used in the plumbing industry for checking temporarily on the pressure of a plumbing system to see if all of the joints are free from leaks and that the proper pressure may be maintained. Usually then the test cap is removed and a permanent valve soldered or bonded onto the tube. The many applications for the coupling is further shown generically in phantom lines in  FIG. 4 , in which the phantom line box is a test cap coupling, a valve, an end unit like a shower-head, a coupling for joining two pieces of tubing together, etc. FIG.  5  shows more specifically the invention for the valve. The details of these different applications are obvious to one of ordinary skill in the art and the details of U.S. Pat. No. 4,911,406 are incorporated herein by reference thereto. 
     In all of the couplings of  FIGS. 1-5 , the invention includes an outer housing  10  having an inner bore  12  with a side wall  14 . The inner bore has a seal support surface  16  against which is fitted a conventional O-ring seal  15 . The seal is held in the bore by a spacer bushing  18 . The spacer bushing has circumferentially spaced axial grooves  33 , as best shown in  FIG. 2 . A metallic gripper ring  27  is provided with circumferentially spaced axially and radially inwardly protruding teeth  29 . The spacer bushing has a flat  36  aligned with a flat  30  on the gripper ring  27 . The inside wall of the housing has a protruding flat  31  to receive the flats on the bushing and gripper ring. The gripper ring is also provided with a notch  39  and the spacer bushing provided with a notch  41 , which notches engage a protrusion  40  ( FIG. 1 ) on the inside wall  14  of the outer housing  10 . The flats on the inner bushing and the gripper ring and the notches are provided to assure proper installation of the gripper ring and inner bushing within the housing. 
     An end bushing  20  is positioned against the gripper ring and holds the O-ring, spacer bushing, and gripper ring tightly together so that the teeth of the gripper ring extend into the inner bore  12 . The end bushing is held within the internal bore of the outer housing  10  by sonic welds  22 . The end bushing has a passageway  24  provided with guide ribs  28  for guiding a plastic or copper tube  26  into the coupling. The tube end inserted into the coupling is shown in phantom lines in  FIG. 1 . Inner ribs  35  are provided in the side wall  14  of the internal inner bore  12 . In general, the gripper ring is made from a full hard stainless steel, the coupling parts from plastic, such as, acetal, or for larger couplings, metal, and the tubes or pipe made from copper or conventional PVC used in plumbing polybutylene, CPVC, PEX or other metals and plastics used in plumbing. 
     As best shown in  FIG. 1 , the coupling is assembled by placing the O-ring against the ring support surface  16 , the spacer bushing is aligned with its flat  36  against the flat  31  of the outer housing and slid into place against the O-ring, the gripper ring is then placed against the spacer bushing with its flat  30  aligning the teeth  29  into the grooves  33  of the spacer bushing. Then the end bushing is placed within the outer housing and welded into place by sonic welding  22 . For metal couplings, the outer housing can be secured by any suitable permanent attachment such as crimped or interfering threads. When a tube  26  is to be inserted in the coupling or the coupling inserted over a tube, the tube and the coupling are moved axially to one another with the tube engaging the teeth. The teeth extend into the inner bore of the housing a distance further than the outer diameter of the tube  26  so that the teeth are deflected by the tube as the tube and housing are moved axially to one another. This creates an immediate gripping engagement of the teeth even before any fluid pressure is applied in the coupling. The tube is inserted until it tightly engages the end wall  50  of the bore  12 . This can be felt by the user of the coupling since the tube can be pushed to move axially, albeit tightly, until the end of the tube stops against the end wall  50  and cannot be pushed any further relative to the outer housing. 
     The O-ring seal maintains the fluid seal around the tube. The tube cannot be solely axially withdrawn by fluid pressure without destroying the coupling and will maintain quite a high fluid pressure. The tube can be removed by unscrewing the coupling relative to the tube. The teeth  29  in the gripper ring can be manufactured with a slight twist or by using the full hard stainless steel or equivalent material, such as manganese, or composites, and a ring thickness of no greater than about 0.012 inches, preferably 0.008 inches, then the twist can be created by the forces acting on the teeth as the tube  26  is simultaneously rotated and pulled out of the housing. By rotating the tube while pulling, edges of the gripper teeth will move within the grooves  33  causing friction on one edge of the teeth allowing the teeth to twist and the tube screw out of the gripper ring. If the tube is initially not inserted past the gripper ring, or is not inserted through the O-ring seal, leakage will be apparent almost immediately when the pressure is applied to the plumbing system. Thus, an advantage of this embodiment is it gives an immediate visual check on the proper placement of the tube within the coupling or the position of the test cap over the coupling. 
       FIG. 4  shows a phantom version of a coupling to illustrate that the coupling could be a test cap as shown in  FIG. 1 , a valve in U.S. Pat. No. 4,911,406, or simply a mirror image of the right side coupling  52  being on the left side to simply join two tubes together. 
       FIG. 5  shows an embodiment using the valve or housing  54  of U.S. Pat. No. 4,911,406 as the coupling. Another advantageous feature of the invention is illustrated in  FIG. 5  by showing that pre-cut lengths of tubing or hose  60  can be bonded and crimped as at  61  or otherwise permanently secured to the valve to provide a complete connection from the plumbing system to an appliance or other plumbing fixture. Thus, installation can be made more economically and faster having a complete pre-cut plumbing connection already made-up and available. 
     As best shown in  FIG. 6 , the unique coupling is shown with multiple gripper rings in one form as a valve. However, while a valve has been shown in the embodiment of  FIG. 6 , this is for illustration purposes only and the coupling can be used for a valve, such as shown in U.S. Pat. No. 4,911,406 or any other use for a coupling. This is shown generically in phantom lines in  FIG. 9 , in which the phantom line box is a valve, a coupling for joining two pieces of tubing together, a shower head, a tub faucet coupling, or any other use where a soft tubular plumbing material is to be joined to more tubing or to some plumbing fixture. These different applications or uses for the coupling are obvious to one of ordinary skill in the art and the details of U.S. Pat. No. 4,911,406 are incorporated herein by reference thereto. 
     In the couplings of  FIGS. 6-11 , the invention includes an outer housing  110  having an inner bore  112  with a side wall  114 . The inner bore has a seal support surface  116  against which is fitted a conventional O-ring seal  115 . The seal is held in the bore by a spacer bushing  118 . The spacer bushing has circumferentially spaced axial grooves  133 , as best shown in  FIG. 7 . A metallic gripper ring  127  is provided with circumferentially spaced axially and radially inwardly protruding teeth  129 . A second identical gripper ring  132  is provided against the O-ring seal and thus on the opposite side of the spacer bushing  118 . The spacer bushing has a flat  136  aligned with a flat  130  on the gripper rings  127 ,  132 . The inside wall of the housing has a protruding flat  131  to receive the flats on the bushing and gripper rings. The gripper rings are also provided with a notch  139  and the spacer bushing provided with a notch  141 , which notches engage a protrusion or key  140  ( FIG. 6 ) on the inside wall  114  of the outer housing  110 . The flats on the inner bushing and the gripper rings and the notches are provided to assure proper installation of the gripper rings and inner bushing within the housing. 
     An end bushing  120  is positioned against the gripper ring  127  and holds the O-ring, spacer bushing, and gripper rings tightly together so that the teeth of the gripper rings extend into the inner bore  112 . The end bushing is held within the internal bore of the outer housing  110  by sonic welds  122  ( FIG. 10 ). The end bushing is provided with an inner bore  124  and protruding guide ribs  128  for guiding a plastic or copper tube  126  into the coupling. In the alternative, these ribs can be eliminated so that existing old repaired plumbing tubing with existing ferrules can be fitted into larger diameter of the end bushing  120  as in  FIG. 13 . The tube end inserted into the coupling is shown in  FIG. 6 . Inner ribs  135  ( FIG. 7 ) are provided in the side wall  114  of the internal inner bore  112 . In general, the gripper rings are made from a full hard stainless steel, the coupling parts from plastic, such as, acetal, or for larger couplings, metal, and the tubes or pipe made from copper, conventional PVC, polybutylene, PEX, or other metals and plastics used in plumbing. 
     As best shown in  FIG. 6 , the coupling is assembled by placing the O-ring against the ring support surface  116 , the gripper ring  132  is placed against the O-ring, the spacer bushing is aligned with its flat  136  against the flat  131  of the outer housing and slid into place against the gripper ring  132 , the gripper ring  127  is then placed against the opposite side of the spacer bushing with its flat  130  aligning the teeth  129  into the grooves  133  of the spacer bushing. Then the end bushing is placed within the outer housing and welded into place by sonic welding  122 . For metal couplings, the outer housing can be secured by any suitable permanent attachment such as crimped or interfering threads. As noted above and as can be seen in figures, the end bushing holds the O-ring, spacer bushings and gripper rings tightly together so that the teeth of the gripper rings extend into the inner bore and are retained therein in a stationary position prior to insertion of the the tube into the inner bore and no mechanism is provided to adjustably move the gripper rings within the inner bore or relative the the tube prior or during the gripper rings engaging the tube. The gripper rings are held tightly in place within the inner bore awaiting engagement with the tube when the tube is inserted into the inner bore. By so holding the O-ring, spacer bushings and gripper rings tightly together within the inner bore without any mechanism provided for adjustment of the position of the gripper rings or the O-ring and spacer bushings, the spacer bushings and the peripheral portions of the gripper rings are no-movably and non-adjustably retained by the housing and end bushing against axial movement within the inner bore. Further, the teeth of the gripper rings are non-retractable prior to engagement with the tube and no mechanism is provided to retract or adjustably or otherwise move the teeth prior to engagement with the tube when inserted into the inner bore. When a tube  126  is to be inserted in the coupling or the coupling inserted over a tube, the tube and the coupling are moved axially to one another with the tube engaging the teeth. The teeth of both rings extend into the inner bore of the housing a distance further than the outer diameter of the tube  126  so that the teeth are deflected by the tube as the tube and housing are moved axially to one another. This creates an immediate gripping engagement of the teeth even before any fluid pressure is applied in the coupling. The tube is inserted until it tightly engages the end wall  150  ( FIG. 10 ) of the bore  112 . This can be felt by the user of the coupling since the tube can be pushed to move axially, albeit tightly, until the end of the tube stops against the end wall  150  and cannot be pushed any further relative to the outer housing. 
     The O-ring seal maintains the fluid seal around the tube. The tube cannot be solely axially withdrawn by fluid pressure without destroying the coupling and will maintain quite a high fluid pressure. The tube can be removed by unscrewing the coupling relative to the tube, although with softer plastic tubing the teeth may dig into the tubing more deeply and the gouged surface of the tubing may be damaged when the coupling is unscrewed. In this case, a new tube may be needed or the damaged section of the original tube can be cut-off and the remaining undamaged end of the tubing can then be re-inserted into the coupling. The teeth  129  in the gripper rings can be manufactured with a slight twist or by using the full hard stainless steel or equivalent material, such as manganese, or composites, and a ring thickness of no greater than about 0.012 inches, preferably 0.008 inches, then the twist can be created by the forces acting on the teeth as the tube  126  is simultaneously rotated and pulled out of the housing. By rotating the tube while pulling, edges of the gripper teeth will move within the grooves  130  causing friction on one edge of the teeth allowing the teeth to twist and the tube screw out of the gripper ring. 
     In the embodiments shown, if the tube is initially not inserted past the gripper ring, or is not inserted through the O-ring seal, leakage will be apparent almost immediately when the pressure is applied to the plumbing system. Thus, an advantage of this embodiment is it gives an immediate visual check on the proper placement of the tube within the coupling or the position of the valve over the coupling. 
       FIG. 8  shows a typical gripper ring. 
       FIG. 9  shows a phantom version of a coupling  152  to illustrate that the coupling could be a valve, a coupling joining two tubes, a faucet coupling, a shower head, a test cap, or any other plumbing fixture using a push on coupling. 
       FIG. 10  shows another embodiment with the same features of the invention but with more gripper rings (three, namely,  127 ,  177 , and  187  being shown) and more spacers  118 ,  178 , and  188 . 
       FIG. 11  shows an embodiment using the coupling as a test cap. A test cap is used in a plumbing system to see if all of the joints are free from leaks and that the proper pressure may be maintained. Usually then the test cap is removed and a permanent cap soldered or bonded onto the tube. 
       FIG. 12  shows another embodiment similar to  FIGS. 10 and 11  but with a spacer  118   a  placed between the o-ring and the gripper ring. 
       FIG. 13  shows a valve having an O-ring seal  115  and one or more gripper rings, preferably two, such as, gripper rings  130  and  132 . The end bushing in this embodiment is tapered internally as at  210  so that the metal compression ring  202  of a conventional metal threaded compression type valve fitting can fit into the taper  210  and allow the end of the pipe with the compression ring left intact on the pipe, pushed into the valve until it is past the O-ring seal and with the compression ring abutting the tapered surface of the end bushing. In this embodiment, the push-on valve of this invention replaces the conventional screw on compression fitted valve. The compression nut  200  from the old valve may be left on the pipe exposed or can be pushed back into the hole in the wallboard where it is hidden. The location of the O-ring axially inward of the gripper rings is advantageously employed in this re-piping embodiment because it allows the free end of the pipe of the replaced pipe fitting to be inserted far enough into the valve to pass inside the O-ring and be effectively sealed even though the end of the pipe may not reach the end of the internal bore  112  when the compression ring engages the tapered surface  210  of the end bushing. The gripper rings will, of course, hold the pipe in the valve and within the O-ring seal. 
     While two and three gripper rings have been shown in the drawing, any multiple of gripper rings can be used within the spacing of the coupling. 
     While the preferred embodiments have been illustrated and described, it should be apparent that variations will be apparent to one skilled in the art. Accordingly, the invention is not to be limited to the specific embodiments shown in the drawings.