US Patent 7287784 Fire-blocking door lock structure

A fire-blocking door lock structure is mounted on a fire-blocking door including a frame member, a push handle and a casing. The casing has the bottom thereof fixed to a plate member and connected to a base body. The fire-blocking door lock structure includes a middle latch mechanism mounted in the casing, an upper latch mechanism and a lower latch mechanism symmetrically mounted on opposite sides of the middle latch mechanism and connected to the middle latch mechanism, and an actuation mechanism connected to the middle latch mechanism. When the push handle is pressed, the actuation mechanism is driven to actuate the middle latch mechanism, and the upper latch mechanism and the lower latch mechanism are simultaneously actuated by the middle latch mechanism to unlatch the door lock. When the push handle is released, the door lock is restored to the lock-up status.