Method and apparatus for controlling the concentration of carbon dioxide in an aircraft cabin

摘要

A control and method for maintaining the concentration of carbon dioxide in the cabin (11) of an aircraft at a desired level. A carbon dioxide sensor (40, 41) is disposed to monitor the concentration of carbon dioxide in the cabin of the aircraft. Air drawn from the cabin at locations (24, 25) where the concentration of carbon dioxide is relatively higher than at other locations (31, 32) is selectively vented overboard or recirculated in response to the concentration of carbon dioxide in the cabin. As more air is vented overboard to maintain the cabin at a desired level of carbon dioxide concentration, an air pack compensates by supplying additional pressurized fresh air to the cabin. Should the cabin pressure drop below a minimum set point limit, the control causes less air to be vented overboard, irrespective of the carbon dioxide concentration. In another embodiment, cabin pressure is controlled between predetermined limits, and so long as the pressure remains between those limits, additional pressurized fresh air is provided if the level of carbon dioxide increases beyond a predetermined limit.