Abstract:
A threadless flared fitting for mechanically connecting fluid transmission lines includes a diametrically guided sealed piston to engage the flared tube connection. This piston is axially spring loaded and designed to apply a hydrostatic force on the engaged flared connection. Axial clamping preload is provided by a compressed mechanical spring and the hydrostatic pressure force on the sealed piston will reinforce the clamping force in the flared connection and prevent separation.

Description:
DISCLOSURE DOCUMENT 
     This application contains subject matter which is set forth in the U.S. Patent Disclosure Document Number 499878, dated Sep. 13, 2001. 
     FIELD OF INTENTION 
     The invention relates to power transmission flow conductor fittings and particularly to flared tubing connections without the use of threaded connections. The sealing integrity of the line connection is a major consideration. 
     BACKGROUND OF INVENTION 
     Most tube and hose connections feature engagement for fastening flared transmission lines and depend upon the mechanical clamping force applied to frusto-conical engaged surfaces of the fitting for sealing. 
     Most of the current threadless transmissions line connections feature elastomeric sealing elements which depend upon compression to initiate and maintain the fluid seals. The frusto-conical shaped engagement joint common to the flared fittings is not utilized. 
     These threadless connectors are usually limited to relatively low pressure (less than about 500 psi) fluid transmission applications because of their limited sealing integrity. Such threadless connectors are typically utilized in some automotive fluid systems and in some domestic plumbing installations. 
     There are many advantages of a threadless tube fittings for connecting fluid transmission lines: 
     A. Reduced manufacturing and installation costs 
     B. Simplified installation 
     C. Applicable in inaccessible installation (limited space for using a wrench) 
     D. Elimination of possible leakage source, damaged threads, and 
     E. Rapid installation and disassembly. 
     SUMMARY OF INVENTION 
     The present invention provides an internal mechanism in the engaged flared connection of a transmission line to maintain a sealed joint without a torqued-threaded fastener. 
     The internal mechanism comprises a hollowed piston featuring a frusto-conical shaped surface for engaging and sealing the flared end of a transmission line. Said piston contains a radial sealing means to seal its radial clearance with the bore and to isolate the end which is axially spring biased and exposed to the pressure of the transmitted fluid. The resulting hydrostatic pressure axial force on the piston supplements the compressed mechanical spring force applied at the assembly of the fitting connection. The combination of the mechanical spring force and the hydrostatic pressure force assures sealing contact of the engaged frusto-conical shaped surface with the flared end of the tubing. 
     The applied hydrostatic force is proportional to the pressure of the transmitted flow in the transmission line. 
     A mechanical spring is internally compressed between the hollowed piston and a shoulder within the bored body to prevent the piston frusto-conical shaped end from losing seal contact with the flared end of the tubing during low pressure flows. 
     At assembly of the line connection an axial force is applied against the flared tubing to displace the hollowed piston and to compress the spring means so as to insert a retention ring into the circular groove located in the bore. Part of the retention ring axially supports the enlarged flared end of the tubing to prevent it from being disengaged by the force of the compressed spring means and by the hydrostatic pressure force. 
     The engaged frusto-conical shaped end of the piston and the flared end of the tubing are preloaded by the compressed spring at assembly of the fitting. As the pressure of the transmitted flow increases, the resulting hydrostatic pressure force increases on the joint to ensure contact and prevent separation. 
     Unlike the prior art of the threadless fitting connectors relying exclusively on an “O” ring to simultaneously seal two (2) annular clearances to prevent external leakage, the threadless flared fitting connector hereof provides a more dependable “O” ring seal of one annular clearance and a surface-to-surface sealing frusto-conical contact which is axially spring preloaded at assembly and axially loaded further by a hydrostatic force correlated to the pressure of the transmitted fluid. 
     Because of the superior sealing feature in the present invention fitting connector it is anticipated that its fluid pressure capability should be at least 50 percent greater than the current state-of-the-art threadless fitting connectors. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a sectional view of a threadless tube fitting connection which is typical of the prior art. 
     FIG. 2 is a sectional view of the subassembly consisting of the fitting components prior to its installation in the receiving body, this view displays a first preferred embodiment of the invention. 
     FIG. 3 is a sectional view of the receiving body in which the subassembly described in FIG. 2 is installed to complete the fitting connection. The receiving body is part of the first preferred embodiment of the invention. 
     FIG. 4 is a sectional view of the threadless flared tube assembly this view shows the preferred assembly embodiment of the invention. 
     FIG. 5 is a sectional view of a modified version for the threadless flared tube fitting connection with the preferred embodiment of FIG.  3 . Included is the illustration of the hydrostatic pressure force distribution in the fitting for maintaining the seal contact at the flared tube connection. 
     FIG. 6 is a sectional view of multiple threadless flared tube connections of the preferred embodiment of the invention in a single receiving body. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 illustrates a prior art threadless tube fitting connection  20  comprised of a tubing  21  which is crimped at one end to shoulder an “O” ring  22  which is axially contained by a spacer  23  and a washer  24 . The listed components are located as a subassembly for installation in a bore  25  which is located in a receiving body  26 . The subassembly is retained in the bore  25  by an expansion ring  27 . The sealing is dependent upon the hydrostatic pressure to radially and axially deform the “O” ring  22  and seal the two (2) radial clearances  28  and  29  of the rim dimensions of the spacer  23 . 
     FIG. 2 displays a preferred embodiment of the invention in a threadless flared tube fitting connection subassembly  30  comprising the flared tubing  31 , a hollowed piston  32 , an annular seal  33 , and a mechanical spring means  34 . The flared end  38  of the tubing provides a shoulder  35  to support the retention of an expansion ring  36 . The hollowed piston  32  features a frusto-conical shaped end  37  for receiving the flared end  38  of tubing  31  and for forming a joint  40 . The annular seal  33  is located axially and radially in recess on piston  32 . Piston  32  possess pilot diameters  39  for guidance and radial support respectively in the tubing  31  and in the receiving body  41  which is shown in FIG.  3 . 
     The displayed subassembly  30  is installed in the receiving body  41  which is shown in FIG. 3 
     FIG. 3 displays the bore  42  in body  41  receiving the subassembly  30  which is shown in FIG.  2 . The length of the bore determines the amount of assembled compression on the spring means  34  and the amount of preload that can be applied on joint  40 . A groove  43  is located near the entrance of bore  42  that receives the expansion ring  36  to retain the axially preloaded subassembly  30 . 
     The reduced diameter bore  44  directs the transmitted flow to the system. Shoulder  45  supports the compression of the spring means  34 . 
     FIG. 4 displays a preferred embodiment of the invention of the threadless flared tube fitting connection assembly  45 . Piston  32  provides the frusto-conical shaped end  37  for engaging the flared end  38  of tubing  31  and forms a joint  40 . Pilot diameters  39  of piston  32  align the tubing  31  and bore  42  in body  41 . The spring  34  is compressed during installation, the compressive force is supported at the shoulder  35  on the flared tubing and retained by the expansion ring  36  located in groove  43 . 
     A back-up sealing ring  51  is assembled as part of the sealing means  33  to resist extrusion by high pressure of the transmitted flow. 
     FIG. 5 displays another preferred embodiment of the invention and illustrates the principle forces, F 1  and F 2 , that maintain the sealing contact on the flared joint  40  connection. In this assembly  58 , piston  32  is replaced by piston  50  which is modified version that contains the embodied features of the invention. Piston  50  provides a close annular interfit between the rim diameter  52  and bore  42 . and the centering effect of the frusto-conical shaped end  37  to align the engagement of flared end  38  of tubing  31  to form a joint  40 . The compressed spring  34  applies mechanical force F 1  on joint  40  at assembly of the fitting connection. The hydrostatic pressure force F 2 , a product of the net exposed annular area of the rim diameter  52  and of the fluid pressure in flow passage  53 , will add to the assembly contact force on joint  40  to prevent separation. 
     An intervening malleable seat  63  is located on the frusto-conical shaped end  37  and engaged with the flared end  38  of tubing  31  to form joint  40 . A spacer  54  with a beveled surface compensates for the flared surface  55  and to effect a flat support surface  56  for the expansion ring  36  in groove  43 . 
     The spring force F 1  prevents separation of joint  40  at low pressure of the transmitted flow in passage  53 . The annular seal  33  seals the radial clearances between the bore  42  and rim diameter  52 . The radial clearance  62 , at the flared joint  40 is exposed to atmospheric pressure. The resulting hydrostatic force F 2 , a product of the net exposed annulus area of the rim diameter  52  and the pressure in the flow passage  53 , will supplement the assembly mechanical spring force F 1  applied to the flared joint  40  to prevent separation. 
     The hydrostatic force F 2  is proportionally affected by the pressure in flow passage  53 . 
     FIG. 6 displays another preferred embodiment, assembly  60 , of the invention comprising of more than one threadless flared tubing connections in a common body  41 . In each flared joint  40 ,the flared end  38  engages the frusto-conical shaped end  37 . The engagement of the rim diameter  52  of piston  50  in bore  42 , and the centering effect of the frusto-conical shaped end  37  on the flared end  38  of tubing  31  aligns the engagement of the flared joint  40 . The compressed spring  34  is retained by the installed expansion ring  36 . 
     The seal  33  may comprise a plurality of sealing rings of combined resilient and plastic material. The spring  34  may comprise a wave spring washer, a beveled spring washer or a helical coil spring. 
     By the above description there is disclosed a novel construction for a threadless flared tube fitting for connecting flow conductors affording a more secured leak-proof assembly compared to the similar purpose connectors of the prior art. The versatility, flexibility, and higher pressure capability afforded thereby should be instantly recognized by those skilled in the art. 
     Since many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the drawings and specification shall be interpreted as illustrative and not in a limiting sense.