Separation nut

Claim 2

A separation nut for releasably engaging a threaded element, comprising: a housing having an internal cavity, an aperture to receive an element to be engaged by the nut, and a gas port communicating with the cavity; a seat member fixed to the housing and extending around said aperture, said seat member facing into the cavity and tapering inwardly as it extends into the cavity; anti-rotation means fixed relative to the housing; a plurality of nut segments, each having a concave surface bearing a fragment of the same thread facing in an inward direction and engaged by the anti-rotation means, a lock surface and a relief surface, both facing in an outward direction, and a pair of abutment surfaces, one at each end of the segments, the segments being grouped around a central axis with one of their abutment surfaces bearing against the seat member; an axially-extending lock cylinder in said cavity; a lock piston slidably fitted in said lock cylinder, said lock piston including a lock surface so proportioned and arranged as to embrace and hold the segments in said grouped condition when it overlaps their lock surfaces, an engagement shoulder, and a head having a driving face and a deceleration face, and an axially-extending buffer cylinder in said lock piston; a buffer piston slidably fitted in said buffer cylinder in fluid-sealing contact therewith, a power chamber being formed in said buffer cylinder between the buffer piston and said driving face, an abutment face on the opposite side of the buffer piston from the power chamber so disposed and arranged as to bear against the other of said abutment surfaces of the nut segments; a shoulder on said buffer piston facing and radially overlapping the engagement shoulder of the lock piston, whereby said shoulders can engage one another, the gas entry port communicating with the power chamber, and restraint means for holding the lock piston against the buffer piston and thereby holding the buffer piston against the nut segments, with the lock surface of the lock piston overlapping the lock surfaces of the nut segments, the restraint means releasing the lock piston for axial motion after the exertion of sufficient fluid pressure on the lock piston, whereby upon the exertion of said sufficient fluid pressure, the lock piston is axially shifted so that its lock surface overlaps the relief surfaces of the nut segments and not their lock surfaces, the buffer piston presses against the segments to move them radially outward, and the sHoulder on the lock piston engages the shoulder on the buffer piston with an accompanying dissipation of kinetic energy, a deceleration chamber being formed in the cavity between the housing and the deceleration face, displacement of the lock piston being resisted in the deceleration chamber; a neck on said housing entering the deceleration chamber and passing through the head of the lock piston; and seal means extending between said neck and the head of the lock piston, which seal means is exposed to the power chamber.

Claim 3

A separation nut according to claim 1 in which the lock piston is tubular, in which the head is an internal annulus, and in which the annular head makes a sliding, fluid-sealing fit with an external cylindrical surface on the neck.

Claim 4

A separation nut according to claim 2 in which the buffer cylinder is formed in the tubular portion of the lock piston.

Claim 5

A separation nut for releasably engaging a threaded element, comprising: a housing having an internal cavity, an aperture to receive an element to be engaged by the nut, and a gas port communicating with the cavity; a seat member fixed to the housing and extending around said aperture, said seat member facing into the cavity and tapering inwardly as it extends into the cavity; anti-rotation means fixed relative to the housing; a plurality of nut segments, each having a concave surface bearing a fragment of the same thread facing in an inward direction and engaged by the anti-rotation means, a lock surface and a relief surface, both facing in an inward direction, and a pair of abutment surfaces, one at each end of the segments, the segments being grouped around a central axis with one of their abutment surfaces bearing against the seat member; an axially-extending lock cylinder in said cavity; a lock piston slidably fitted in said lock cylinder, said lock piston including a lock surface so proportioned and arranged as to embrace and hold the segments in said grouped condition when it overlaps their lock surfaces, an engagement shoulder, and a head having a driving face and a deceleration face, and an axially-extending buffer cylinder in said lock piston; a buffer piston slidably fitted in said buffer cylinder in fluid-sealing contact therewith, a power chamber being formed in said buffer cylinder between the buffer piston and said driving face, an abutment face on the opposite side of the buffer piston from the power chamber so disposed and arranged as to bear against the other of said abutment surfaces of the nut segments; a shoulder on said buffer piston facing and radially overlapping the engagement shoulder of the lock piston, whereby the said shoulders can engage one another, the gas entry port communicating with the power chamber, and restraint means for holding the lock piston against the buffer piston and thereby holding the buffer piston against the nut segments, with the lock surface of the lock piston overlapping the lock surfaces of the nut segments, the restraint means comprising a peripheral groove in the wall of the lock cylinder, and a radially compressible ring adapted to expand into the said groove to hold the lock piston in a predetermined position until sufficient force is exerted on the lock piston to remove the ring from the groove, releasing the lock piston for axial motion after the exertion of sufficient fluid pressure on the lock piston, whereby upon the exertion of said sufficient fluid pressure, the lock piston is axially shifted so that its lock surface overlaps the relief surfaces of the nut segments and not their loc surfaces, the buffer piston presses against the segments to move them radially outward, and the shoulder on the lock piston engages the shoulder on the buffer piston with an accompanying dissipation of kinetic energy, a deceleration chamber being formed in the cavity between the housing and the deceleration face, displacement of the lock piston being resisted in the deceleleration chamber; a neck on the housing entering through the deceleration chamber and throUgh the head of the lock piston; and seal means extending between said neck and the head of the lock piston, which seal means is exposed to the power chamber.

Claim 6

A separation nut for releasably engaging a threaded element, comprising: a housing having an internal cavity, an aperture to receive an element to be engaged by the nut, and a gas port communicating with the cavity; a seat member fixed to the housing and extending around said aperture, said seat member facing into the cavity and tapering inwardly as it extends into the cavity; anti-rotation means fixed relative to the housing; a plurality of nut segments, each having a concave surface bearing a fragment of the same thread facing in an inward direction and engaged by the anti-rotation means, a lock surface and a relief surface, both facing in an inward direction, and a pair of abutment surfaces, one at each end of the segments, the segments being grouped around a central axis with one of their abutment surfaces bearing against the seat member; an axially-extending lock cylinder in said cavity; a lock piston slidably fitted in said lock cylinder, said lock piston including a lock surface so proportioned and arranged as to embrace and hold the segments in said grouped condition when it overlaps their lock surfaces, an engagement shoulder, and a head having a driving face and a deceleration face, and an axially-extending buffer cylinder in said lock piston; a buffer piston slidably fitted in said buffer cylinder in fluid-sealing contact therewith, a power chamber being formed in said buffer cylinder between the buffer piston and said driving face, an abutment face on the opposite side of the buffer piston from the power chamber so disposed and arranged as to bear against the other of said abutment surfaces of the nut segments; a shoulder on said buffer piston facing and radially overlapping the engagement shoulder of the lock piston, whereby the said shoulders can engage one another, the gas entry port communicating with the power chamber, and restraint means for holding the lock piston against the buffer piston and thereby holding the buffer piston against the nut segments, with the lock surface of the lock piston overlapping the lock surfaces of the nut segments, the restraint means comprising a peripheral groove in the wall of the lock cylinder, and a radially compressible ring adapted to expand into the said groove to hold the lock piston in a predetermined position until sufficient force is exerted on the lock piston to remove the ring from the groove, releasing the lock piston for axial motion after the exertion of sufficient fluid pressure on the lock piston, whereby upon the exertion of said sufficient fluid pressure, the lock piston is axially shifted so that its lock surface overlaps the relief surfaces of the nut segments and not their loc surfaces, the buffer piston presses against the segments to move them radially outward, and the shoulder on the lock piston engages the shoulder on the buffer piston with an accompanying dissipation of kinetic energy, a deceleration chamber being formed in the cavity between the housing and the deceleration face, displacement of the lock piston being resisted in the deceleleration chamber; a neck on the housing entering through the deceleration chamber and throUgh the head of the lock piston; and seal means extending between said neck and the head of the lock piston, which seal means is exposed to the power chamber.