Redundant seal ring coupling assembly

Claim 1

In a coupling assembly, first and second tubular fluid passage-defining structures, means for relatively drawing said structures axially together to assemble said structures in coupled relation to each other, a first formation forming a part of said first structure, a second formation forming a part of said second structure and cooperating with said first formation to define a cavity between said structures, said cavity extending circumferentially around the longitudinal axes of said structures and being disposed radially outwardly from the fluid flow passages through said structures, said first formation being formed with a first axially extending tubular end portion having a radially inwardly facing cylindrical surface delimiting said cavity, said second formation being formed with a second axially extending tubular end portion disposed radially inwardly of said first tubular end portion and having a radially outwardly facing cylindrical surface delimiting said cavity, said second tubular end portion being spaced from and unsupported by said first structure, said radially inwardly facing and radially outwardly facing cylindrical surfaces being radially spaced apart and axially overlapping each other when said structures are axially drawn together, said first formation being further formed with a circumferentially extending surface lying in a conical envelope and intersecting said radially inwardly facing cylindrical surface to define an inwardly opening circumferentially extending corner delimiting said cavity, said second formation being further formed with a circumferentially extending surface lying in a conical envelope and intersecting said radially outwardly facing cylindrical surface to define an outwardly opening circumferentially extending corner delimiting said cavity, said inwardly and outwardly opening corners being in diagonally opposed relation to each other, first and second interchangeable, equally sized torsionally deflectable seal rings received in said cavity, each of said seal rings having a pair of diagonally opposite corner edges and being torsionally deflectable about its cross section from a straightened configuration to a conical configuration in which it establishes a seal between said structures, said first and second formations engaging said seal rings to axially urge said seal rings into abutment with each other and to thereafter torsionally deflect each of said seal rings about its cross section to its conical configuration as said structures are axially drawn together to increase the radial dimension of each of said seal rings through its cross section for radially compressively loading each of said seal rings at its diagonally opposite corner edges and thereby establishing seals at the lines of contact between the diagonally opposite corner edges of each of said seal rings and said formations, said first seal ring having one of its diagonally opposite corner edges seated in said inwardly facing corner and the other of its diagonally opposite corner edges seating against said radially outwardly facing cylindrical surface in its torsionally deflected, seal-establishing condition, and said second seal ring having one of its diagonally opposite corner edges seated in said outwardly opening corner and the other of its corner edges seating against said radially inwardly facing cyindrical surface in its torsionally deflected, seal-establishing condition, the torsional deflection of said seal rings being initialized by engagement of only one of said corners with the assembly of said first and second seal rings, whereby only one of said corners is utilized to initialize torsional deflection of both of said seal rings, the deflected conical configuration of each of said seal rings lying along a conical envelope whose apex angle decreases as the seal ring is deflected from a relaxed condition to its torsionally deflected, seal-establishing condition, and stop abutment surface means limiting axial displacement of said first and second formations toward each other to limit the extent to which said seal rings are torsionally deflected by said first and second formations.