Patent ID: 8500526

Claim:
A cabin pressure control system in an aircraft, comprising: a cabin pressure outflow valve control sub-system configured to control outflow valves of the aircraft; and a cabin pressure relief sub-system configured to operate independently of and simultaneously with the cabin pressure outflow valve control sub-system, including: a pressure relief valve with a closure member; an actuator for the closure member; a pressure relief valve control unit configured to produce command signals to open or close the pressure relief valve; a function generator operable simultaneously with but independently from the cabin pressure outflow valve control sub-system and programmed with a desired parametric relationship among parameters: aircraft altitude; desired cabin-to-ambient pressure differential (desired ΔP); and a predetermined limit of variation between desired ΔP and actual cabin-to-ambient pressure differential (actual ΔP); the function generator adapted to produce cabin-to-ambient pressure differential (ΔP) command signals based on a state of the parameters, the ΔP command signals produced independently from any command signals produced by the cabin pressure outflow valve sub-system; and the actuator being adapted to rotate responsively to the ΔP command signals and actual ΔP to open the closure member of the pressure relief valve as needed to reduce excessive variations between actual ΔP and desired ΔP.