Releasable folding link member for providing opening torque

Details Releasable folding link member for providing opening torque Releasable folding link member for providing opening torque

1990-06-29

1993-01-12

Stodola, Daniel P.

Rotary shafts, gudgeons, housings, and flexible couplings for ro

Coupling accommodates drive between members having...

Coupling transmits torque via radially directed pin

403100, 464901, F16D 360, B64G 900, E04H 1560

Patent

active

051785838

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention relates to linkages for rotatably joining two parts of a structure together, and specifically provides for two members to be joined together in a first attitude until, on deployment for example, they are released and automatically take up a second, rigid attitude.
2. Discussion of Prior Art
Such linkages are known and used, for example, for folding rod or tubular members of a structure intersected by nodes. The object in this arrangement is for the structure to be folded into a minimum volume for transportation, and for it to open automatically into a specific, fixed relationship when required. A particular requirement for this is the deployment of skeletal structures used as space platforms: these have to be stowed as compactly as possible in the launch vehicle and need to be erected reliably and as automatically as possible. The types of joint used hitherto for such purposes have usually been bulky, have required additional components to restrain the initial impulsion rate, and have contained separate locking elements.


SUMMARY OF THE INVENTION

According to this invention, a linkage comprises a rod member; a sleeve slidable over a bifurcated, cylindrical end portion of the rod member; a link member pivoted within the ends of the said end portion and having two parallel sides profiled to provide a sliding fit within the sleeve, an angled side portion against which the end of the sleeve is urged when the linkage is in a partly open position and a rounded, profiled end portion to provide clearance for the sleeve when the linkage is opening; means for limiting the sliding movement of the sleeve on the end portion; and a coil spring located around the end portion and between one end of the sleeve and a step on the rod member to provide a torque for opening the linkage when released from the closed position.
The rod member may comprise a rod or tube into which a shaft having a bifurcated end is rigidly secured, the shaft constituting the end portion of the rod member and providing a seat along which the sleeve is slideable and for the coil spring which extends from the end of the tube to the sleeve.
The link member may be an appendage to a base unit, for example, or a multiple joint may include a plurality of similar link members, but in an alternative and preferred form the link member may be symmetrical in form and be pivotally attached in similar fashion to two similar rod members and the invention may provide a linkage for interconnecting two rod members by the said link member.
Whilst the link member as described need have an angled side portion at one or both ends of only one of its two parallel sides, a more adaptable linkage may result if a similar angled side portion is provided at one or both ends of the other parallel side. The linkage may readily be released from the locked, open position by withdrawing the sleeve from the link member against the action of the spring, and if the link member is in the latter form then the rod member may be rotated in either direction into the closed position.
The angled side portions are preferably formed at an angle in the range 5.degree. to 15.degree. to the parallel sides of the link member, an angle of 10.degree. being found particularly suitable in one form of construction, but the extent of the angled side portion must not be too great to cause the length of the parallel sides to be insufficient to provide rigidity when engaged in the open position inside the sleeve.


BRIEF DESCRIPTION OF THE DRAWINGS

By way of example, embodiments of the invention will now be described with reference to the drawings, of which
FIG. 1 is a side elevation of a linkage in the closed position,
FIG. 2 is an enlarged section on the mid-plane of the link member of the linkage illustrated in FIG. 1,
FIG. 3 is a partly cut-away perspective view of the linkage in a partly open position,
FIG. 4 is a side elevation of the linkage in the locked, open position,
FIG. 5 is a perspective view of an alternative arrangemen

REFERENCES:
patent: 738554 (1903-09-01), Lingel
patent: 895372 (1908-08-01), Hostetter et al.
patent: 1504889 (1924-08-01), Hansen
patent: 1906218 (1933-04-01), Patchell
patent: 2066182 (1936-12-01), Lenz
patent: 2762210 (1956-09-01), Redard
patent: 4437480 (1984-03-01), Husa
patent: 4527579 (1985-07-01), Knotter et al.
patent: 4753259 (1988-06-01), Hansen et al.

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