US Patent 9677772 Intelligent ventilating safety range hood control system

An improved control system for a range hood that is capable of automatically responding to various air quality parameters including heat, smoke, carbon monoxide, humidity, and others. The system contains a number of features that, combining aspects of open-loop and closed loop control, manage the system dynamics for smoother operation, respond to both level and rate signals and compensate for background conditions and sensor variability by using relative values.