US Patent 9869117 Door closer

A door closer with an electric motor-assisted closing feature, that may generate its own power to assist in closing, and controls the speed of opening and closing of the door during generation is disclosed. Embodiments of the present disclosure are realized by a motorized door closer that electrically creates a latch boost force for a closing door. The door closer includes a motor disposed to operatively connect to a door so that the door will be moved toward closed when the motor moves, and a position sensor to determine a position of the door. A processor is programmed to exert a closing force on the door in the latch boost region or when it otherwise detects that a motor assist is needed.