Temporally staged rapid panel access fastener for highly curved panels

摘要

A fastener for highly curved access panels on aircraft or other structures, featuring a bottom-grasping design allowing for an unblemished outer panel surface, simple and rapid pneumatic fastener actuation, built-in clamping pre-load, and full retractability of the fastener inside the supporting structure. The fastener includes a Belleville spring with a piston centrally disposed therein, where the piston and spring deflect outward upon application of pneumatic pressure. A pressure chamber within the piston has inlet and outlet orifices designed so that the pressure in the piston chamber gradually increases, requiring several seconds to reach a pressure which causes locking dogs in the piston to deploy radially into a cavity in the access panel. When pressure is removed, the Belleville spring relaxes, the locking dogs grasp a lip of the cavity, and the access panel is latched onto the structure with a clamping pre-load. A pneumatic sequence for unlatching is also provided.