Duct joint

Claim 1

A flexible duct joint for connecting one end of a first duct in gastight communication with one end of a second duct, comprising: a first spherically shaped bearing member arranged for connection in a gastight sealing relationship around said one end of said first duct to extend outwardly therefrom symmetrically with respect to the longitudinal axis thereof; a second spherically shaped bearing member, the inner spherically shaped peripheral surface of said second bearing member substantially conforming with the outer spherically shaped peripheral surface of said first bearing member, the outer and inner peripheral surfaces, respectively, of said first and second bearing members being spherically shaped bearing races; structure for coupling said second bearing member to said second duct and holding said one end of said first duct adjacent said one end of said second duct with the inner peripheral surface of said second bearing member overlapping, adjacent and in alignment with the outer peripheral surface of said first bearing member whereby said bearing members are free to rotate and angulate whenever said ducts rotate and angulate relative to each other, said structure coupling said second bearing member to said second duct including a hold down means mounted on said first bearing member for holding said second bearing member in its overlapping, adjacent, aligned relationship to said first bearing member and also detachably coupling said second bearing member to said second duct; ball bearing means positioned between and in contact with said bearing races; means for selectively securing said coupling structure in its coupled position; annular seal gland structure arranged for connection in a gastight sealing relationship around said one end of said second duct and defining adjacent the spherically shaped outwardly extending inner peripheral surface of said first bearing member a seat for an annular seal member; said seat being defined by an outwardly positioned stop, an inwardly positioned lip and a bearing surface extending between said stop and lip; said stop and lip being for retaining a seal member within said seat; said bearing surface substantially conforming in shape to the inner peripheral surface of said first bearing member; said stop having a height greater than the height of said lip but less than the distance between said bearing surface and the inner peripheral surface of said first bearing member; a substantially rigid backup ring mounted in said seat of said seal gland structure adjacent said stop in position to support and thereby prevent extrusion of a seal member positioned therein, said backup ring extending outwardly from said bearing surface a distance greater than the height of said stop to contact the inner peripheral surface of said first bEaring member, said backup ring being made of a material having lubricating characteristics so as to reduce the friction between said first bearing member and said backup ring; an annular seal member fitted in said seat between said backup ring and said lip to seal the region within said joint between the inner peripheral surface of said first bearing member and said seal gland structure; said annular seal member being made of a resilient material; said seal member having outer and inner lips which extend at an angle to the plane defined by its annular body substantially equal to the outward slant of the inner peripheral surface of said first bearing member, said lips defining, respectively, the outer and inner peripheries of said seal member and said seal member including a flat base portion joining said lips and extending substantially perpendicularly thereto to define a seal member back; a gas pocket being defined in said seal member by said lips and base portion which opens at the front edge of said lips; said seal member being fitted in said seal gland structure with said base portion adjacent said backup ring, said outer lip bearing against the inner peripheral surface of said first bearing member, said inner lip bearing against said bearing surface and said gas pocket defined in said seal member communicating with the interior of said joint so that pressurized fluid being conducted therethrough enters said gas pocket to force said lips in tight sealing relationship against said seal gland structure and said first bearing member, said stop, backup ring and seal member base portion extending substantially perpendicular to said bearing surface; and a springlike liner positioned in the gas pocket of said annular seal member to force said sealing lips apart and reinforce said gas pocket.