FIELD

The present disclosure relates generally to locking and unlocking structures, and more particularly, to locking and unlocking structures using a shape memory alloy (SMA).

BACKGROUND

Locking apparatuses can be employed in various environments to allow structures (e.g., doors, cabinets, stowbins, windows) to be locked and unlocked. For example, an aircraft may include a locking actuator for preventing an undesired opening of an aircraft door and for unlocking the aircraft door during an emergency scenario or when power has otherwise been removed from the locking actuator.

These and other existing locking apparatuses often include a complex arrangement of components such as solenoids, electric motors, bearings, springs, weights, and screw gears. However, existing locking apparatuses can be complex and often contain more components than desired, which can increase the time spent designing and installing such apparatuses. For example, existing locking actuators for aircraft doors typically include redundant components required to return the doors to an unlocked state after power is removed from the locking actuators. The complexity of existing locking apparatuses can also increase the cost and time spent manufacturing and installing such locking apparatuses.

What is needed is a less complex locking apparatus that can reliably lock and unlock structures when desired.

SUMMARY

In an example, a method for locking and unlocking a structure is described. The method comprises attaching a first end of a pawl to a support assembly, where the pawl comprises a shape memory alloy (SMA) element configured to transition between a first configuration and a second configuration, and where the pawl is attached to the support assembly such that a second end of the pawl is movable between a locked position that prevents a rotatable shaft from rotating via engagement of the second end of the pawl with a lug of the rotatable shaft and an unlocked position that allows the rotatable shaft to rotate via disengagement of the second end of the pawl from the lug, activating the SMA element, thereby causing the SMA element to take on the first configuration and move the second end of the pawl to the locked position, and deactivating the SMA element, thereby causing the SMA element to take on the second configuration and move the second end of the pawl from the locked position to the unlocked position.

In another example, a locking apparatus is described. The locking apparatus comprises a support assembly, a rotatable shaft comprising a lug, and a pawl. The pawl comprises a SMA element configured to transition between a first configuration and a second configuration, where a first end of the pawl is attached to the support assembly such that a second end of the pawl is movable between a locked position that prevents the rotatable shaft from rotating via engagement of the second end of the pawl with a lug of the rotatable shaft and an unlocked position that allows the rotatable shaft to rotate via disengagement of the second end of the pawl from the lug. When the SMA element is activated, the SMA element takes on the first configuration and moves the second end of the pawl to the locked position, and when the SMA element is deactivated, the SMA element takes on the second configuration and moves the second end of the pawl from the locked position to the unlocked position.

The features, functions, and advantages that have been discussed can be achieved independently in various examples or may be combined in yet other examples. Further details of the examples can be seen with reference to the following description and drawings.

