Auxiliary lock with a control plate for preventing unlatching from outside

摘要

An auxiliary lock includes an exterior lock assembly having a knob and an actuating plate that is connected to the knob to rotate therewith. A casing is mounted inside a door for rotatably supporting a knob that is also connected to the actuating plate to rotate therewith. A control plate is mounted in the casing and includes a first end extended beyond the casing for manual operation. A second end of the control plate includes a notch releasably engaged with one of a number of teeth of an engaging wheel mounted in the casing. The control plate is movable vertically and retained in place by a positioning element. The engaging wheel is connected to the actuating plate to rotate therewith.