Hinged door locking device that automatically opens and closes based on temperature

Fire-responsive automatic unlocking device for hinged doors using bimetallic bending deformation

This technology features a pusher in the door frame's catch box spring-loaded toward the latch, a blocker with a through-hole, and a bimetal connecting the blocker to the catch box. In a fire, the bimetal bends due to heat, causing the pusher to pass through the hole and press the latch, allowing the door to open without turning the handle.

During building fires, indoor temperatures can spike to around 800°C during flashover, making door handles too hot to touch. Conversely, opening a door during an advanced fire can be dangerous due to incoming flames and heat. Existing locks lack the ability to distinguish between temperature stages to manage these risks.

This technology uses a pusher with side protrusions that catch on or pass through the blocker based on the degree of bimetallic bending. At a certain temperature, it presses the latch to allow egress; at higher temperatures, the pusher disengages to keep the door closed. It is ideal for apartment entrances, hotel rooms, and office escape routes, providing temperature-based, power-free, sensor-free fire safety.

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Key Features:

• A catch box installed in the door frame and a pusher installed in the catch box, spring-loaded toward the latch
• A blocker with a through-hole positioned between the pusher and the latch, and a bimetal connecting the blocker to the catch box
• A structure where, during a fire, the bimetal bends, causing the pusher to pass through the hole to press the latch, with side protrusions catching or passing through the blocker based on the degree of bending
• A structure where the pusher, inserted linearly into the catch box, disengages after the protrusions pass through the hole, releasing the latch pressure

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