Joints and connections – Manually releaseable latch type – Having operating mechanism
Reexamination Certificate
1998-10-08
2001-03-20
Knight, Arthur (Department: 3629)
Joints and connections
Manually releaseable latch type
Having operating mechanism
Reexamination Certificate
active
06203237
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to the field of apparatus for releasably attaching expendable stores such as a fuel tank to a vehicle and the like and, in particular, to an apparatus that is quickly resettable.
2. Description of Related Art
There are numerous approaches to releasably connecting expendable stores to a vehicle. For example, wing mounted gravity released weapons are attached to the wings of aircraft by means of bomb racks that incorporate retractable hooks that engage lugs on the weapon and uses external adjustable sway braces to prevent lateral motion. The hooks can be either electro-mechanically or explosively actuated. However such apparatus are limited to small expendables. The use of such an approach on a large external fuel tank mounted to a spacecraft would require massive external sway braces that would add significant weight to the spacecraft and increase drag to unacceptable levels.
On large external fuel tanks explosively actuated systems such as explosive bolts and the like have proven highly reliable, but require refurbishment after each use. In addition, during the installation of pyrotechnic devices, concurrent activities are severely restricted, increasing the overall “turnaround” time between launches. For example, U.S. Pat. No. 5,520,476 “Tie-Down And Release Mechanism For Spacecraft” by C. W. Marks, et al. discloses such an explosively actuated device. It includes a hollow housing mounted within the main body of the spacecraft having an internal lip at its end that abuts against an internal lip on a second hollow housing on the structure to be released. A segmented collet, having an external groove, is held in contact with the two lips such that they are retained within the groove. The collet in turn is held into contact with the lips by a toroidal spring supported by a movable cylinder. This cylinder includes a second groove positioned such that when the movable cylinder is actuated by the pyrotechnic charges, it drives the cylinder to a position where the spring can retract into the second groove thereon allowing the segmented collet to release the lips. Such explosively actuated systems can not be used on vehicles that require multiple dockings with another spacecraft because of the refurbishment requirement after each use. In the future, reusable booster spacecraft will require rapid turn around times and thus such vehicles must have only a minimum number of systems requiring refurbishment between launches.
U.S. Pat. No. 4,431,333 “Apparatus For Releasably Connecting First and Second Objects in Predetermined Space Relationship” by J. A. Chandler and U.S. Pat. No. 5,364,046 “Automatic Compliant Capture And Docking Mechanism For Spacecraft” by M. E. Dobbs, et al. disclose apparatus for connecting a spacecraft to another spacecraft. Here one of the vehicles includes an extendable probe having a bulb-like member at its end which engages a cone shaped funnel on the spacecraft. Upon the bulb like member bottoming in the funnel, a releasable detente secures the probe therewithin. Such systems, have the advantage of correcting for misalignment of the two vehicles during docking because the funnel tends to “capture” the probe. However, they are unusable for securing an expendable tank or the like to a launch vehicle. First of all, the need to accommodate misalignment is not required and the tank must be firmly secured to the booster in order to withstand the high aerodynamic and inertial G loads experienced by boosters. In addition, they do not provide means for adjusting the tension preload between the spacecraft nor are such systems retractable to a flush condition.
Thus, it is a primary object of the invention to provide an apparatus for releasably connecting first and second structures together, such as a reusable launch vehicle and an expendable external tank.
It is another primary object of the invention to provide an apparatus for releasably connecting first and second structures together that requires no refurbishment after operation.
It is a further object of the invention to provide an apparatus for releasably connecting first and second structures together that includes means to adjust the tension preload.
It is a still further object of the invention to provide an apparatus for releasably connecting first and second structures together that returns to a flush position within the external contour of the structure.
SUMMARY OF THE INVENTION
The invention is an apparatus for releasably connecting a first structure to a second structure such as a spacecraft and expendable fuel tank. In detail, the invention includes the first structure having a first cavity extending inward from an external surface thereof. The first cavity incorporates an inward facing circumferencial lip in proximity to the first surface thus forming a restricted opening therein.
A second cavity is located in the second structure that extends inward from an external surface thereof. A hollow tubular member is movably mounted within the second cavity and incorporates a collet at a first end. When the two structures are positioned for joining the cavities are aligned and in proximity to each other. The tubular member is movable between a retracted position flush or recessed within the second cavity to an extended position wherein the collet on the first end extends into the first cavity. The collet includes a plurality of longitudinal slots extending from the first end partially along the tubular member toward the second end forming a plurality of finger-like members in the form of very stiff leaf springs. In one embodiment, the plurality of fingers is bent radially inward forming a segmented generally truncated conical surface. The fingers include radially outward directed protrusions at the first end of the tubular member forming a segmented circular ring having a diameter smaller than the diameter of the restricted opening of the lip in the first cavity (the retracted position of the collet).
A shaft having first and second ends is slidably mounted within the tubular member and is movable between a retracted position to an extended position wherein in the first end is engagable with the fingers of the collet. When the tubular member and shaft are in the extended positions, the shaft forces the fingers, which are biased toward the retracted position, from the retracted position to the expanded position such that the protrusions have a diameter greater than the diameter of the circumferential lip locking the first and second structures together.
In a second embodiment, the fingers are straight and biased toward the expanded position, and the diameter of the protrusions is greater than the diameter of the restricted opening in the first cavity (expanded position). In this embodiment, when the tubular member is moved to the extended position, the fingers are compressed inward to the retracted position as the protrusions pass through the restricted opening in the lip and thereafter expand the expanded position. Thereafter, when the shaft, is moved to the extended position, it locks the protrusions in engagement with the lip.
A first actuator assembly is coupled to the tubular member for moving it from the retracted position to the extended position. Preferably, the fist actuator assembly includes the tubular member having external threads in proximity to the second end. A first nut having internal threads engages these external threads and further has external spines. An electric motor operating through a gear reduction assembly is coupled to the splines of the first nut for rotating the nut clockwise and counterclockwise such that the tubular member is driven between the retracted and extended positions. Furthermore, once the shaft and tubular member are in the extended positions and the first and second structures are locked together, the electric motor, operating through the gear reduction assembly, can be used to adjust the tension load therebetween.
A second actuator assembly is included for moving the shaft between the retracte
Bresnik Edwin J
Buck Peter A.
Peralta Gregory
Swift Thomas R.
Cottingham John R.
Knight Arthur
Lockheed Martin Corporation
Schruhl Robert A.
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