Patent ID: 6790257
Filing Date: 2004-09-14
Classification: B01D,F24F,Y02B

Abstract:
An airflow feedback control method for use with a fan filter unit of the type having a fan rotor and a bell nozzle having an inlet and an outlet, for the purpose of controlling the fan filter unit to generate a constant amount of airflow equal to a preset desired amount;the airflow feedback control method comprising the steps of: (1) measuring the pressure difference between the inlet and the outlet of the fan filter unit; (2) obtaining the value of airflow amount corresponding to the pressure difference between the inlet and the outlet of the fan filter unit; (3) comparing the value of airflow amount against a preset value representing the desired airflow amount to thereby obtain an airflow error signal; and (4) utilizing the airflow error signal to adjust the speed of the fan filter unit to thereby adjust the amount of airflow from the fan filter unit; and then utilizing the newly-resulted pressure difference between the inlet and the outlet as feedback parameter to obtain a new airflow error signal to adjust the speed of the fan rotor until the amount of airflow from the fan filter unit is substantially equal to the preset desired amount.