US Patent 8955194 Fire door hinge with fusible pin

A closures mechanism for a door actuated during a fire, which causes the door to automatically close. The present invention provides a hinge with opposing hinge plates comprising a door leaf and a frame leaf each pivotal around a hinge pin and spring. A hinge spring nub is anchored within a channel having a fusible block that prevents the spring nub and tension from traveling the channel. At a predetermined temperature the fusible block ruptures causing the spring nub and spring tension to move into engagement with the door attached to the hinge door leaf thereby causing the door to close by means of the tensioned spring's kinetic energy.