Patent ID: 7950987

Claim:
A control unit for controlling aircraft cabin pre-pressurization rate during take-off, comprising: a cabin pressure command circuit for receiving signals from a cabin temperature sensor and for producing a cabin pressure command signal; a first comparator for comparing the cabin pressure command signal with a sensed cabin pressure signal and producing a cabin pressure error signal; a rate command circuit responsive to the cabin pressure error signal and operable to supply cabin pressure rate-of-change commands; a second comparator configured to receive a predetermined cabin pressure rate-of-change value and sensed cabin pressure rate-of-change values and operable, in response thereto, to supply cabin pressurization rate error values representative of a difference between the predetermined cabin pressure rate-of-change limit value and the sensed cabin pressure rate-of-change values; and a rate limiter coupled to receive the cabin pressure rate-of-change commands and the cabin pressurization rate error values and operable, in response thereto, to (i) select a cabin pressurization rate limit from a finite set of discrete cabin pressurization rate limit values, the selection made according to the cabin pressurization rate errors and (ii) limit the cabin pressure rate-of-change commands to prevent the cabin pressurization rate from exceeding the selected cabin pressurization rate limit.