Mechanical dereefer

Details Mechanical dereefer Mechanical dereefer

1999-12-23

2001-07-10

Jordan, Charles T. (Department: 3644)

Aeronautics and astronautics

Safety lowering devices

Parachutes

C244S152000, C244S150000, C244S147000, C244S15100A

Reexamination Certificate

active

06257524

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates generally to a device for selectively holding and releasing lines and more particular to a device for releasing reefing lines on parachute canopies or the like.
The use of parachutes, either for air dropping heavy payloads or decelerating high speed aircraft, requires the incorporation of suitable means to regulate the opening of the parachute canopy. If not regulated, deceleration of the payload caused by rapid parachute canopy opening is excessive, imposing potentially destructive forces on the attached payload. Additionally, for payloads delivered using multiple parachutes, the opening of each parachute must be controlled so that no single parachute interferes with, or “starves”, the opening of the remaining parachutes. To control the opening rate of such parachute canopies, so-called reefing lines are employed, typically encircling the rim of the parachute canopy. The reefing line ends are held by a dereefing device and the reefing line is sized so that the parachute canopy cannot fully open as long as the reefing line ends are held. The dereefing devices are associated with timers or barometrically controlled devices, which after a given time or at a given altitude release the reefing line ends, enabling full opening of the parachute canopy. Multiple differently sized reefing lines may be used for each parachute canopy, with each reefing line released sequentially so that the canopy can be opened in controlled stages, allowing further control over payload deceleration.
When the canopy is opened it imposes a force on the reefing line which is transferred to the reefing device. In known dereefing devices, this force tends to hold or lock the parts of the device together. Thus, known dereefing devices must be capable of overcoming the locking force created by taut reefing lines to ensure release of the reefing line ends.
Dereefing devices can generally be classified into either destructive or nondestructive types. The destructive types include those using explosive charges or mechanically actuated blades to sever the reefing line. While destructive dereefing devices are less susceptible to reefing line loads, they do not allow reuse of the reefing line and/or the dereefing devices themselves. Nondestructive dereefing devices typically capture a reefing line end loop around a pin. The pin is releasably held within a yoke. The pin is withdrawn from the yoke to release the reefing line and loops. As previously discussed, this arrangement allows the taut reefing line to hold or lock the pin to the yoke.
SUMMARY OF THE INVENTION
The invention in a preferred form is a mechanical dereefer comprising a frame with a bifurcated end defined by spaced frame plates and an opposing housing end. The housing end includes a base and housing walls orthogonal to the base which define a frame cavity within. A latch, comprising a latch body and a latch arm angularly mounted to the latch body, is mounted between the spaced plates of the bifurcated end. The latch arm and latch body define a line receiving cavity. The latch mounting allows pivotal movement between a capture position and a release position. In the capture position, a reefing line end loop is captured around the arm and within the line receiving cavity and prevented from sliding off of the arm by cooperation of the arm and frame. In the release position, the tension imposed by the taut reefing line pulls the reefing line end loop off of the arm. Preferably, the latch comprises a pair of opposing latch arms symmetrically mounted to the latch body to create a respective pair of the line receiving cavities. In this manner two reefing line end loops may be accommodated by a single inventive mechanical dereefer.
An elongated latch lock has an internal end located within the frame cavity and an opposing external end which is slidable between projected and withdrawn positions through an opening in a first housing wall. The latch lock is biased toward the withdrawn position by a tension member mounted between the latch lock interior end and a frame wall. In the projected position, the latch lock external end abuts a latch body shoulder to maintain the latch in the capture position. In the withdrawn position, the latch lock exterior end is displaced from the latch shoulder, so that the latch is free to pivot to the release position.
An elbow link is pivotally mounted within the frame cavity. The elbow link includes a first arm defining an elongated slot which mounts to the latch lock. The elbow link includes a second arm angularly offset from the first arm which terminates in a sear end. Preferably the sear end comprises a bi-leveled tip. The elbow link pivotal mounting is in the general location of the intersection of the first and second arms.
A trigger link is also pivotally mounted within the frame cavity. The trigger link includes a trigger end, engageable with the elbow link sear end, and an actuation end, which is movable within an aperture defined by a second housing wall.
In use of a preferred embodiment, a loop of the reefing line is placed around each latch arm and the latch is pivoted to the capture position. The elbow link is pivoted so that the latch lock exterior end engages the latch shoulder and the trigger link is actuated so that the trigger end engages the elbow link sear end. With the trigger and elbow link thus engaged, the latch lock is maintained in a semi-stable condition in contact with the latch shoulder, holding the reefing line ends secured. When release of the reefing line ends is desired, the trigger lever is actuated so that the trigger end is disengaged from the elbow link sear end, allowing the latch lock to be biased toward the withdrawn position. Once the latch lock exterior end is away from the latch shoulder, the latch is free to pivot under the tension imposed by the reefing lines to the release position, allowing the reefing lines to pull free of the latch arms. The use of a pivotal latch allows any force imposed by a taut reefing line to be used to actuate the latch, in contrast to conventional designs which are bound up by such reefing line force.
An object of the invention is to provide a new and improved mechanical dereefing device.
Another object of the invention is to provide a nondestructive dereefing device which utilizes loads imposed by taut reefing lines to aid activation.
A further object of the invention is to provide a mechanical dereefing device which can be quickly and easily reset for reuse.


REFERENCES:
patent: 612194 (1898-10-01), Clough
patent: 1618321 (1927-02-01), Woods
patent: 2665163 (1954-01-01), Gross
patent: 3034750 (1962-05-01), Sieverts
patent: 4249765 (1981-02-01), Janssen
patent: 4291852 (1981-09-01), Simmons
patent: 5464301 (1995-11-01), Kramer
patent: 5832571 (1998-11-01), Kanamori
patent: 6126115 (2000-10-01), Carrier et al.

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