Patent attributes
A room pressure controlling system having a supply air valve, a common exhaust air valve, controllers, and a differential pressure sensor. The controller gradually changes a supply and an exhaust airflow rates when there is an airflow rate change controlling operation, and calculates, based on a setting value and a pressure difference that is measured by the differential pressure sensor, a correction control output value for the valve being operated as the room pressure controlling valve, and if the sum value of the control output value and the correction control output value is a value that causes operation of the room pressure controlling valve in the direction opposite of the desired direction, suspends the output of the sum value, but if the value causes the room pressure controlling valve to operate in the desired direction, outputs the sum value to the room pressure controlling valve.
