US Patent 7735261 Self-locking door assembly

A preferred embodiment of a self-locking door assembly includes a door whose hinged-side connects to one side of a door frame by at least one hinge having two pivot joints. One of the pivot joints is mounted to the door frame and the other is mounted to the inside of the door. The free end of the door carries a latch member which engages an underside of the opposite side of the door frame when the door is partially or fully closed. After the latch engages the frame, forcing the hinged side of the door closed causes the hinge to toggle, holding the door closed under force and takes up play in the pivot joints and/or latch. For security, the pivot joints and latch are concealed when the door assembly is closed.