Inflatable seal

Claim 2

An inflatable annular seal comprising a closed loop having oppositely disposed peripheral sealing surfaces, said loop including a body of gas-impervious elastomeric material formed with an internal chamber, said body providing at least one flexible wall means movable between first and second positions in response to changes in fluid pressure within said chamber for causing at least one of said sealing surfaces to move between operative and inoperative positions, said wall means remaining substantially in said first position with said one sealing surface substantially spaced from its operative position when the pressure in said chamber exceeds the pressure on the exterior of said seal by less than a predetermined positive differential pressure and moving to said second position causing said one sealing surface to move to its operative position only when such differential pressure exceeds said predetermined differential pressure, said internal chamber being continuous, said body being formed with an elongated section joined at its ends, and said wall means being free of peripherally directed tensile stresses when said wall is in either of said positions, said wall means being concave in one of said positions and being convex in the other of said positions.

Claim 3

An inflatable annular seal as set forth in claim 1 wherein said wall means has longitudinally extending sides, and means are provided to maintain a substantially constant spacing between said sides.

Claim 4

An inflatable seal comprising a closed loop having oppositely disposed peripheral sealing surfaces, said loop including a body of gas-impervious elastomeric material formed with an internal chamber, said body providing at least one flexible wall means movable between first and second positions in response to changes in fluid pressure within said chamber for causing at least one of said sealing surfaces to move between operative and inoperative positions, said wall means remaining substantially in said first position with said one sealing surface substantially spaced from its operative position when the pressure in said chamber exceeds the pressure on the exterior of said seal by less than a predetermined positive differential pressure and moving to said second position causing said one sealing surface to move to its operative position only when such differential pressure exceeds said predetermined differential pressure, said wall means being provided with at least one peripherally extending integrally formed rib within said internal chamber which operates to resist movement of said wall means from said first position to said second position.

Claim 5

An inflatable seal comprising a closed loop having oppositely disposed peripheral sealing surfaces, said loop including a body of gas-impervious elastomeric material formed with an internal chamber, said body providing at least one flexible wall means movable between first and second positions in response to changes in fluid pressure within said chamber for causing at least one of said sealing surfaces to move between operative and inoperative positions, said wall means remaining substantially in said first position with said one sealing surface substantially spaced from its operative position when the pressure in said chamber exceeds the pressure on the exterior of said seal by less than a predetermined positive differential pressure and moving to said second position causing said one sealing surface to move to its operative position only when such differential pressure exceeds said predetermined differential pressure, said wall means being provided with at least one peripherally extending integrally formed rib within said internal chamber which operates to resist movement of said wall means from said first position to said second position.

Claim 6

An inflatable annular seal as set forth in claim 3 wherein said internal chamber is continuous, said wall means is the inner wall of said loop and the material forming said wall means and rib are subjected to increased compressive stress as said wall means moves from said first position to said second position.

Claim 7

An inflatable annular seal as set forth in claim 4 wherein said material of said wall means is substantially free of stresses when said wall is in said first position.

Claim 8

An inflatable annular seal comprising a closed loop having oppositely disposed peripheral sealing surfaces, said loop including a body of gas-impervious elastomeric material formed with a continuous internal chamber, said body providing at least one flexible wall movable between first and second positions in response to changes in fluid pressure within said chamber for causing at least one of said sealing surfaces to move between operative and inoperative positions, said wall remaining substanTially in said first position when the pressure in said chamber exceeds the pressure on the exterior of said seal by less than a predetermined positive differential pressure and moving to said second position only when such differential pressure exceeds said predetermined differential pressure, said wall being provided with at least one peripherally extending integrally formed rib which operates to resist movement of said wall from said first position to said second position, said wall being the inner wall of said loop and the material forming said wall and rib are subject to increased compressive stress as said wall moves from said first position to said second position, said material of said wall being substantially free of stresses when said wall is in said first position, said body includes at least one elongated member of substantially uniform cross section with at least one of its ends joined to an adjacent similar end, and a bridging element extends between said ends and provides a seal joint therebetween.

Claim 9

An inflatable annular seal comprising a closed loop having oppositely disposed peripheral sealing surfaces, said loop including a body of gas-impervious elastomeric material formed with a continuous internal chamber, said body providing at least one flexible wall movable between first and second positions in response to changes in fluid pressure within said chamber for causing at least one of said sealing surfaces to move between operative and inoperative positions, said wall remaining substanTially in said first position when the pressure in said chamber exceeds the pressure on the exterior of said seal by less than a predetermined positive differential pressure and moving to said second position only when such differential pressure exceeds said predetermined differential pressure, said wall being provided with at least one peripherally extending integrally formed rib which operates to resist movement of said wall from said first position to said second position, said wall being the inner wall of said loop and the material forming said wall and rib are subject to increased compressive stress as said wall moves from said first position to said second position, said material of said wall being substantially free of stresses when said wall is in said first position, said body includes at least one elongated member of substantially uniform cross section with at least one of its ends joined to an adjacent similar end, and a bridging element extends between said ends and provides a seal joint therebetween.

Claim 10

An inflatable annular seal as set forth in claim 6 wherein said bridging element is a substantially rigid element embedded into the material of each of said ends.

Claim 11

An inflatable annular seal as set forth in claim 7 wherein said bridging element is U-shaped and connects said ends excepting along said flexible wall.

Claim 12

An inflatable annular seal as set forth in claim 8 wherein said bridging element provides the only positive connection between said ends.

Claim 13

An inflatable annular seal as set forth in claim 9 wherein said body is a one piece extruded member joined at its ends.

Claim 14

An inflatable seal comprising a closed loop having oppositely disposed peripheral sealing surfaces, said loop including a body of gas-impervious elastomeric material formed with an internal chamber, said body providing at least one flexible wall means movable between first and second positions in response to changes in fluid pressure within said chamber for causing at least one of said sealing surfaces to move between operative and inoperative positions, said wall means remaining substantially in said first position with said one sealing surface substantially spaced from its operative position when the pressure in said chamber exceeds the pressure on the exterior of said seal by less than a predetermined positive differential pressure and moving to said second position causing said one sealing surface to move to its operative position only when such differential pressure exceeds said predetermined differential pressure, said seal including a member resiliently urging said wall toward said first position and placing the material of said wall in compression when said wall is in said first position.

Claim 15

An inflatable seal comprising a closed loop having oppositely disposed peripheral sealing surfaces, said loop including a body of gas-impervious elastomeric material formed with an internal chamber, said body providing at least one flexible wall means movable between first and second positions in response to changes in fluid pressure within said chamber for causing at least one of said sealing surfaces to move between operative and inoperative positions, said wall means remaining substantially in said first position with said one sealing surface substantially spaced from its operative position when the pressure in said chamber exceeds the pressure on the exterior of said seal by less than a predetermined positive differential pressure and moving to said second position causing said one sealing surface to move to its operative position only when such differential pressure exceeds said predetermined differential pressure, said seal including a member resiliently urging said wall toward said first position and placing the material of said wall in compression when said wall is in said first position.

Claim 16

An inflatable annular seal as set forth in claim 11 wherein said member is in tension and is formed of elastic material extending along the outer peripheral surface of said loop, and said wall is adjacent to said member.

Claim 17

An inflatable annular seal as set forth in claim 12 wherein said body is substantially free of tensile stresses in both of said first and second positions.

Claim 18

A shaft seal comprising in combination a housing assembly providing a pair of opposed axially spaced radially extending shoulders cooperating with an axially extending wall to define an annular groove, a shaft extending past said groove, an inflatable closed loop seal in said groove around said shaft, said seal including a body of gas-impervious elastomeric material formed with an internal chamber, said body providing at least one flexible wall means movable between a first position spaced from said shaft and a second position in sealing engagement with said shaft, said wall means remaining substantially in said first position when the pressure in said chamber exceeds the pressure on the exterior of said seal by less than a predetermined positive differential pressure and moving to said second position only when said differential pressure exceeds said predetermined differential prEssure, said wall means moving said second position to said first position when the pressure in said chamber exceeds the pressure exterior of said seal by a predetermined positive value, said internal chamber being continuous, said loop being formed of an elongated body of uniform cross section provided with a joint at its ends, said ends being joined after said seal is positioned around said shaft, said body being substantially free of tensile stresses when said wall means is in either of said positions, one of said shoulders being removable to permit installation and removal of said seal without removing said shaft, said wall means being concave when in said first position and being convex when in said second position.

Claim 19

A shaft seal comprising in combination a housing assembly providing a pair of opposed axially spaced radially extending shoulders cooperating with an axially extending wall to define an annular groove, a shaft extending past said groove, an inflatable closed loop seal in said groove around said shaft, said seal including a body of gas-impervious elastomeric material formed with an internal chamber, said body providing at least one flexible wall means movable between a first position spaced from said shaft and a second position in sealing engagement with said shaft, said wall means remaining substantially in said first position when the pressure in said chamber exceeds the pressure on the exterior of said seal by less than a predetermined positive differential pressure and moving to said second position only when said differential pressure exceeds said predetermined differential prEssure, said wall means moving said second position to said first position when the pressure in said chamber exceeds the pressure exterior of said seal by a predetermined positive value, said internal chamber being continuous, said loop being formed of an elongated body of uniform cross section provided with a joint at its ends, said ends being joined after said seal is positioned around said shaft, said body being substantially free of tensile stresses when said wall means is in either of said positions, one of said shoulders being removable to permit installation and removal of said seal without removing said shaft, said wall means being concave when in said first position and being convex when in said second position.

Claim 20

A shaft seal as set forth in claim 14 wherein said shaft is a propeller shaft of a marine vessel, and said seal prevents flow of water along said shaft when said wall means is in said second position.

Claim 21

A shaft seal as set forth in claim 15 wherein said shaft extends into said vessel through a stern tube, said housing assembly includes a packing gland inboard of said seal, and said housing is releasably connected in sealing engagement with said stern tube.

Claim 22

A shaft seal as set forth in claim 16 wherein said housing is movable along said shaft away from said stern tube to provide access to said one of said shoulders.

Claim 23

A shaft seal as set forth in claim 14 wherein said housing assembly provides a fitting having a tubular extension extending through a wall of said seal other than said flexible wall means into said chamber.

Claim 24

A shaft seal as set forth in claim 18 wherein said fitting is removable and said seal resiliently engages the exterior of said tubular projection at a location spaced from its inner end.

Claim 25

An inflatable annular seal comprising a closed loop having oppositely disposed peripheral sealing surfaces, said loop including a body of gas-impervious elastomeric material formed with a continuous internal chamber, said body providing at least one flexible wall movable between first and second positions in response to changes in fluid pressure within said chamber for causing at least one of said sealing surfaces to move between operative and inoperative positions, said wall remaining substantially in said first position when the pressure in said chamber exceeds the pressure on the exterior of said seal by less than a predetermined positive differential pressure and moving to said second position only when such differential pressure exceeds said predetermined differential pressure, said body being formed of at least one elongated member of substantially uniform cross section with at least one of its ends joined to an adjacent similar end, and a bridging element extends between said ends and provides a seal joint therebetween.

Claim 26

An inflatable annular seal comprising a closed loop having oppositely disposed peripheral sealing surfaces, said loop including a body of gas-impervious elastomeric material formed with a continuous internal chamber, said body providing at least one flexible wall movable between first and second positions in response to changes in fluid pressure within said chamber for causing at least one of said sealing surfaces to move between operative and inoperative positions, said wall remaining substantially in said first position when the pressure in said chamber exceeds the pressure on the exterior of said seal by less than a predetermined positive differential pressure and moving to said second position only when such differential pressure exceeds said predetermined differential pressure, said body being formed of at least one elongated member of substantially uniform cross section with at least one of its ends joined to an adjacent similar end, and a bridging element extends between said ends and provides a seal joint therebetween.