Tube coupling

Claim 1

A preassembled coupling for tubes wherein a final fluid tight joint may be made solely by insertion of a tube therein, said coupling comprising a body having a first bore for receiving a tube, a chamber axially outwardly of and adjacent the first bore and in which a packing ring is received and sealingly engages the tube and a radially outer cylindrical wall of said chamber, a second bore in the body axially outwardly of the chamber and in which a sleeve is received, and an internal thread axially outwardly of the second bore, a transverse shoulder at the bottom of the second bore, a nut threadably engaged with said internal thread, engaged abuttment surfaces on the body and nut fixing the axial position of the nut relative to the body, said sleeve having an inner end wall forming a movable outer wall of said chamber and when there is no fluid pressure in the body being unbiased in either axial direction and being freely moveable between an innermost position and an outer position, said packing ring being subject to pressure of fluid in the inner end of said chamber and moveable thereby into engagement with said sleeve for moving said sleeve to said outer position, said chamber being of an axial length greater than the axial length of the packing when said sleeve is in said innermost position whereby when there is no fluid pressure within the axially inner end of said chamber said packing may move to said inner end and be out of contact with the sleeve when the sleeve is in said innermost position, said nut having a bore therethrough that terminates in a frusto-conical cam surface at the inner end of the nut, said sleeve having a circumferentially continuous inner end surface and an inwardly facing second surface that engages said shoulder when the sleeve is in said innermost position, said sleeve having longitudinal slits at its outer end forming a plurality of circumferentially spaced fingers, said fingers having a radially inwardly projecting rib of smaller diameter then the tube prior to insertion of the tube within the coupling, said fingers having a flare mouth at their outer ends, said sleeve when in said innermost position being out of contact with said cam surface, said sleeve being in engagement with said cam surface when said sleeve is in said outer position whereby the outer ends of said fingers and said rib are contracted radially inwardly by said cam surface and the rib grips the tube for retaining the tube within the coupling.