Abstract:
A fluid coupling assembly includes a first connection member, a second connection member, and a flow sealing member. The first connection member has an exterior surface, an interior surface and a threaded through hole from the exterior surface to the interior surface. The second connection member has a first sealing surface facing the interior surface of the first connection member, and a first flow passage. The first sealing surface is rigidly fixed with respect to the first connection member. The flow sealing member has external threads that mate with the threaded through hole, a second flow passage aligned with the first flow passage of the first member, and a second sealing surface that seals with the first sealing surface around the first and second flow passages upon application of sealing force via rotation of the external threads in the threaded hole.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to coupling of components in flow assemblies. 
     Tubing for delivering fluids must often be coupled with other components of a flow assembly, such as a valve. FIGS. 1A and 1B illustrate a prior art coupling device  10  for coupling tubing to a check valve. Device  10  defines two cylindrical bores  12   a ,  12   b , has a check valve  14  between bores  12   a ,  12   b , and defines two holes  16   a ,  16   b  connecting bores  12   a ,  12   b  to check valve  14 . Two tubing apparatuses  18   a ,  18   b  have internal tubes  20   a ,  20   b , internal conical surfaces  22   a ,  22   b,  external conical surfaces 24 a ,  24   b,  and external threads  26   a ,  26   b  for mating with internal threads  28   a ,  28   b  of bores  12   a ,  12   b . Internal tubes  20   a ,  20   b  define two openings  30   a ,  30   b  and have two sealing faces  31   a ,  31   b . In operation, apparatuses  18   a ,  18   b  are threadingly engaged with bores  12   a ,  12   b . External conical surfaces  24   a ,  24   b  press against internal conical surfaces  22   a ,  22   b,  such that faces  31   a ,  31   b  seal around holes  16   a ,  16   b . Since internal threads  28   a ,  28   b  are within cylindrical bores and extend to the flat bottoms of the bores (“blind holes”), they can be difficult to manufacture. 
     SUMMARY OF THE INVENTION 
     In general, in one aspect, the invention features a fluid coupling assembly including a first connection member, a second connection member, and a flow sealing member. The first connection member has an exterior surface, an interior surface and a threaded through hole from the exterior surface to the interior surface. The second connection member has a first sealing surface facing the interior surface of the first connection member, and a first flow passage. The first sealing surface is rigidly fixed with respect to the first connection member. The flow sealing member has external threads that mate with the threaded through hole, a second flow passage aligned with the first flow passage of the first member, and a second sealing surface that seals with the first sealing surface around the first and second flow passages upon application of sealing force via rotation of the external threads in the threaded hole. 
     Embodiments of this aspect of the invention may include one or more of the following features. The flow sealing member further includes an outer tightening member and an inner flow tube. The inner flow tube is disposed within an internal bore, and defines the second flow passage therethrough. Application of the sealing force causes sealing of the inner flow tube to the outer member. The outer tightening member has the external threads and has an inner conical surface around the internal bore. 
     The flow sealing member further includes a plastic deformable sealer which can be separable from the tightening member. The deformable sealer has an outer conical surface facing the inner conical surface and carrying the second sealing surface. The inner flow tube passes through the deformable sealer. Application of the sealing force via rotation of the external threads in the threaded hole causes sealing of the inner flow tube to the sealer and sealing of the sealer to the outer tightening member. 
     The second connection member includes a circular lip carrying the first sealing surface, and the first connection member has a circular opening for receiving the lip. 
     The second connection member includes a registration structure for aligning the first flow passage with the threaded through hole of the first connection member. The registration structure is a threaded bore communicating with the first sealing surface, and the first connection member has a clearance hole for aligning with the threaded bore. 
     The first and second connection members are made from a rigid material, such as metal, and the flow sealing member is made from a material less rigid than the first and second connection members, such as plastic. 
     The assembly has a plurality of flow sealing members, the first connection member has a plurality of threaded through holes for mating with the external threads of the flow sealing members, and the second connection member has a plurality of first flow passages for aligning with the second flow passages of the flow sealing members. For example, the assembly has two flow sealing members, two threaded through holes, and two first passages for aligning with the two second flow passages. For communicating with the two first flow passages, the sealing surface of the second connection member has an inlet and an outlet. The inlet and the outlet have different sizes, e.g., the inlet is larger than the outlet. A registration structure offset from the inlet and outlet aligns the two first flow passages with the two threaded through holes of the first connection member. 
     The second connection member further includes two check valves disposed in the two first flow passages. The first check valve prevents flow in a first direction, and the second check valve prevents flow in a second direction. 
     The two flow sealing members include a larger flow sealing member and a smaller flow sealing member. The two threaded through holes include a larger threaded through hole for mating with the larger flow sealing member, and a smaller threaded through hole for mating with the smaller flow sealing member. 
     The first and second sealing surfaces comprise a generally conical shape, and the second sealing surface is disposed on the outer tightening member. 
     In general, in another aspect, the invention features a flow assembly having a flow source, a flow destination, and a pump for delivering substance via a flow path from the source to the destination. In addition, the assembly has a fluid coupling assembly disposed within the flow path between the source and the destination. The coupling assembly includes a first connection member, a second connection member, and two flow sealing members. The connection member has an exterior surface, an interior surface and two threaded through holes from the exterior surface to the interior surface. The second connection member has a first sealing surface rigidly fixed with respect to the first member, facing the interior surface and two first flow passages. The two flow sealing members have external threads that mate with the two threaded through holes, two second flow passages aligned with the first flow passages of the first member, and two second sealing surfaces that seal with the first sealing surface around the first and second flow passages upon application of sealing force via rotation of the external threads in the threaded hole. 
     Embodiments of this aspect of the invention may include one or more of the following features. The flow sealing members have inner flow tubes. The inner flow tube of one of the sealing members connects to the flow source, and the inner flow tube of the other sealing member connects to the flow destination. 
     Embodiments of the invention may have one or more of the following advantages. The assembly avoids the necessity of including threading on the inside of a “blind hole” (threading extending to a flat bottom of a bore). The threaded through holes of the first connection member are easier to manufacture than a threaded blind hole. 
     The fluid coupling assembly is easily adaptable for coupling different types of components. For example, the coupling assembly can be used to couple tubing to receiving components other than check valves. 
     The components of the flow sealing member can be standard, commercially available products. 
    
    
     Other features and advantages of the invention will be apparent from the following description and from the claims. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A is a sectional view of a prior art coupling assembly. 
     FIG. 1B is an end view of the prior art coupling assembly of FIG.  1 A. 
     FIG. 2 is an exploded, sectional view of a fluid coupling assembly. 
     FIG. 3 is a sectional view of the assembly of FIG. 2, shown assembled. 
     FIG. 4 is a sectional view of the assembly of FIG. 2 connected to a pump. 
     FIG. 5 is an exploded, sectional view of an alternate embodiment of the assembly of FIG.  2 . 
     FIG. 6 is a perspective view of module  112  according to the invention. 
     FIG. 7 is a top view of the connecting plate  114  according to the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 2, fluid coupling assembly  110  includes a check valve module  112 , a connecting plate  114 , and two flow sealing assemblies  116   a ,  116   b.    
     Check valve module  112  has a circular first sealing surface  118  defining an inlet  120  and an outlet  122 . Inlet  120  is large enough to prevent, e.g., a drop in pressure experienced by fluid entering inlet  120  sufficient to cause degassing or cavitation. The interior  124  of module  112  defines an inflow path  126  in the direction of arrow B, and an outflow path  128  in the direction of arrow A. Interior  124  also includes two check valves  130   a ,  130   b  disposed within flow paths  126  and  128 . Check valve  130   a  prevents flow in the direction of arrow A, and check valve  130   b  prevents flow in the direction of arrow B. Module  112  is disposed within a cylindrical conduit  132 . The structure and operation of module  112  is described more fully in U.S. patent application Ser. No. 09/260,914, entitled “Check Valve Module,” filed the same date as this application, and incorporated herein by reference in its entirety. 
     Connecting plate  114  includes a bottom surface  134 , a top surface  136 , and two threaded through holes  138   a ,  138   b . Through hole  138   a  has a major diameter D 1  of, e.g., about {fraction (5/16)} inches, and hole  138   b  has a major diameter D 2  smaller than diameter D 1 , e.g., about ¼ inch. Bottom surface  134  defines a generally circular opening  140  for receiving a lip portion  141  of module  112 . Opening  140  includes an interior surface  142  for communicating with sealing surface  118  of module  112 . Connecting plate  114  can be fastened to conduit  132  with two screws  143   a ,  143   b  (FIG.  4 ). 
     Referring to FIGS. 6 and 7, module  112  and connecting plate  114  also include registration structures for aligning through holes  138   a ,  138   b  with inlet  120  and outlet  122  respectively. Module  112  has a threaded alignment bore  170  which communicates with surface  118 , and connecting plate  114  has an aligning clearance hole  172  for aligning with the threaded bore. A screw  174  passes through clearance hole  172  and threads into bore  170  to align holes  138   a  and  138   b  with inlet  120  and outlet  122  respectively. The registration structures are described in the U.S. patent application entitled “Check Valve Module.” 
     Flow sealing assemblies  116   a ,  116   b  each include three separate pieces: an interior tube  144   a ,  144   b , a tightening member  146   a ,  146   b , and a deformable sealer  148   a ,  148   b . Tightening members  146   a ,  146   b  have external threads  149   a ,  149   b  for mating with internal threads  150   a ,  150   b  of through holes  138   a ,  138   b  respectively. Tightening members  146   a ,  146   b  also define bores  152   a ,  152   b . Each bore  152   a ,  152   b  defines an interior conical section  154   a ,  154   b  having an interior conical sealing surface  156   a ,  156   b.    
     Deformable sealers  148   a ,  148   b  have exterior conical surfaces  158   a ,  158   b  sized and shaped to mate with interior conical sealing surfaces  156   a ,  156   b  respectively, and second sealing surfaces  160   a ,  160   b  for sealingly engaging first sealing surface  118  of module  112 . Each sealer  148   a ,  148   b  defines an internal cylindrical bore  162   a ,  162   b  for receiving tubes  144   a ,  144   b  respectively. Bore  162   a  has a circular opening  164   a  which is similar in size to inlet  120  of module  112 , and bore  162   b  has a circular opening  164   b  which is similar in size to outlet  122  of module  112 . Thus, when second sealing surfaces  160   a ,  160   b  are pressed against first sealing surface  118  of module  112 , surfaces  160   a ,  160   b  seal around inlet  20  and outlet  22  respectively. Opening  164   a  has a diameter D 2a  of, e.g., about ⅛ inch, and opening  164   b  has a diameter D 2b  of, e.g., about {fraction (1/16)} inch. 
     Tubes  144   a ,  144   b  pass through bores  152   a ,  152   b  respectively, through opening  140  of plate  114 , and through bores  162   a ,  162   b  respectively of deformable sealers  148   a ,  148   b . Tube  144   a  is wider than tube  144   b.    
     In operation, tubes  144   a ,  144   b  are passed through bores  152   a ,  152   b  of tightening members  146   a ,  146   b  respectively, and then passed through bores  162   a ,  162   b  of sealers  148   a ,  148   b  respectively. Tubes  144   a ,  144   b  fit snugly within bores  162   a ,  162   b . Sealers  148   a ,  148   b  are then inserted into conical sections  154   a ,  154   b  of bores  152   a ,  152   b  respectively, such that exterior conical surfaces  158   a ,  158   b  engage interior conical surfaces  156   a ,  156   b  respectively. 
     Next, connecting plate  114  is affixed to conduit  132  using screws  143   a ,  143   b  (FIG.  4 ), such that sealing surface  118  of module  112  firmly engages interior surface  142  of plate  114 . A threaded screw (not shown) is passed through the aligning clearance hole in the connecting plate and into the threaded alignment bore of module  112 , aligning through holes  138   a ,  138   b  with inlet  120  and outlet  122 , respectively. Tightening members  146   a ,  146   b  are then affixed within through holes  138   a ,  138   b  respectively of plate  114  by engaging external threads  149   a ,  149   b  with internal threads  150   a ,  150   b.    
     Engaging threads  149   a ,  149   b  with threads  150   a ,  150   b , aligns openings  164   a ,  164   b  of sealers  148   a ,  148   b  with inlet  20  and outlet  22  of module  112 . Further tightening of the threads pushes interior conical surfaces  156   a ,  156   b  against exterior conical surfaces  158   a ,  158   b  of sealers  148   a ,  148   b , which pushes second sealing surfaces  160   a ,  160   b  firmly against first sealing surface  118 . This tightening action slightly deforms deformable sealers  148   a ,  148   b , thereby firmly sealing surfaces  160   a ,  160   b  to surface  118 . The tightening action also seals interior surfaces  166   a ,  166   b  of bores  162   a ,  162   b  in sealers  148   a ,  148   b  to an outer surface  168   a ,  168   b  of tubes  144   a ,  144   b . FIG. 3 shows fluid coupling assembly  110  assembled. 
     FIG. 4 illustrates a use for coupling assembly  110 . Referring to FIG. 4, tube  144   a i s connected to a fluid source  180 , and tube  144   b  is connected to a fluid destination  182 . A piston  184  is disposed within conduit  132 . Fluid source  180  can be, e.g., a mobile phase for column chromatography, and fluid destination  182  can be, e.g., a column chromatography cartridge, as described in U.S. patent application Ser. No. 09/260,915, entitled “Pump Drive Decoupler,” and U.S. patent application Ser. No. 09/264,846, entitled “Cartridge Sealing Apparatus and Method.” Both the above applications were filed the same date as this application, and are incorporated herein by reference in their entirety. 
     In operation, movement of piston  184  in the direction of arrow B draws fluid from fluid source  144   a , through coupling assembly  110 , and into a chamber  186  within conduit  132 . Movement of piston  184  in the direction of arrow A pushes fluid from chamber  186 , through coupling assembly  110 , and to fluid destination  182 . The operation of piston  184  and the movement of fluid, e.g., through module  112 , is described further in the U.S. patent applications entitled “Pump Drive Decoupler” and “Check Valve Module.” 
     The components of assembly  110  can be manufactured from various materials. Module  112 , plate  114 , and vessel  132  are preferably metal, and the components of flow assemblies  116   a ,  116   b  are preferably plastic. 
     The tightening members and deformable sealers can be ordered commercially from, e.g., UPCHURCH SCIENTIFIC in Oak Harbor, Wash. Tightening member  146   a  can be, e.g., part P-130, a {fraction (5/16-24)} flat bottom male nut. Tightening member  146   b  can be, e.g., part P-230, a {fraction (1/4-28)} flat bottom male nut. Deformable sealers  148   a ,  148   b  can be, e.g., ferrules P-200 and P-300, respectively. 
     Other embodiments are within the scope of the claims. For example, referring to FIG. 5, an inlet  220  and an outlet  222  of a check valve module  212  might have conical indentations  224 ,  226  rather than a flat, circular opening. In this embodiment, two tightening members  246   a ,  246   b  (not to scale) have conical shaped tips  248   a ,  248   b , and the deformable sealers are eliminated. Tips  248   a ,  248   b  have exterior conical sealing surfaces  250   a ,  250   b  which seal with internal conical sealing surfaces  218   a ,  218   b  of indentations  224 ,  226  when pushed into place by a connecting plate (not shown), as described above. Alternatively, instead of tips  248   a ,  248   b , conical deformable sealers oriented in the same direction as tips  248   a ,  248   b  can be used. 
     The deformable sealers and sections  154   a ,  154   b  of bores  152   a ,  152   b  can have a shape other than conical. 
     The size of tubes  144   a ,  144   b  and the bores through which tubes  144   a ,  144   b  are inserted can be varied. Tightening members  146   a ,  146   b  can be affixed to plate  114  using a mechanism other than threads. The shapes of opening  140  and lip  141  can be different, e.g. square. In addition, module  112  need not include a lip  141 , and plate  114  need not include an opening  140 . 
     Instead of module  112 , assembly  110  can include another type of valve, or a non-valve connection member. If a connection member having an inlet but no outlet is used, then coupling assembly  110  can have only one tightening member, one bore in plate, and one deformable sealer. Alternatively, if the connection member used in place of module  112  has more than two receiving openings, then assembly  110  can have more than two tightening members, deformable sealers, and bores.