Fan filter unit

Abstract

A fan filter unit includes a plurality of fan motors, a plurality of detectors, a total controller, and a filter. Each of the fan motors includes a fan and a motor. The total controller performs a feedback control to the respective fan motors so that the detected rotating speeds are identical with a set rotating speed, based on rotating speeds detected by the detectors. When one detected rotating speed value by any of the detectors is smaller than the other detected rotating speed value by the other detector, the total controller performs a tuning control of rotating speed so that a rotating speed of the other fan motor is adjusted to the slower rotating speed of the fan motor.

1 . A fan filter unit comprising:
 a first fan motor having a first fan and a first motor;   a first detector configured to detect a rotating speed of the first motor;   a second fan motor having a second fan and a second motor;   a second detector configured to detect a rotating speed of the second motor;   a filter configured to clean air blown from the first fan and the second fan; and   a total controller configured to perform a feedback control so that a rotating speed of the first fan motor is identical with a set rotating speed based on the rotating speed detected by the first detector, to perform a feedback control so that a rotating speed of the second fan motor is identical with the set rotating speed based on a rotating speed detected by the second detector, to perform a tuning control of rotating speed so that the rotating speed of the second fan motor is reduced to the rotating speed detected by the first detector when the rotating speed detected by the first detector is slower than the rotating speed detected by the second detector by at least a predetermined value, to perform a tuning control of rotating speed so that the rotating speed of the first fan motor is reduced to the rotating speed detected by the second detector when the rotating speed detected by the second detector is slower than the rotating speed detected by the first detector by at least a predetermined value.   
     
     
         2 . The fan filter unit according to  claim 1 , wherein
 the total controller includes:
 a first rotation controller configured to perform a feedback control so that the rotating speed of the first fan motor is identical with a set rotating speed based on the rotating speed detected by the first detector; 
 a second rotation controller configured to perform a feedback control so that the rotating speed of the second fan motor is identical with the set rotating speed based on the rotating speed detected by the second detector; 
 a first comparator configured to compare the rotating speed detected by the first detector with the set rotating speed and to transmit a comparison result to the first rotation controller; 
 a second comparator configured to compare the rotating speed detected by the second detector with the set rotating speed, and to transmit a comparison result to the second rotation controller; 
 a third comparator configured to calculate a difference between the rotating speed detected by the first detector and the rotating speed detected by the second detector; and 
 a rotating speed tuning controller configured to perform a tuning control so that the rotating speed of a faster fan motor among the first fan motor and the second fan motor is reduced via one of the first and second rotation controllers when a calculation result of the third comparator is at least the predetermined value, upon receiving the calculation result of the third comparator. 
   
     
     
         3 . The fan filter unit according to  claim 1 , wherein
 the total controller is configured to delay a start of the tuning control of rotating speed by a predetermined time.   
     
     
         4 . The fan filter unit according to  claim 3 , wherein
 the predetermined time is set a time required for a preparatory operation during which the rotation speeds detected by the first detector and the second detector are stabilized, just after one of the start of the operation of the fan filter unit and a change of the set rotation speed for the fan motors.   
     
     
         5 . The fan filter unit according to  claim 1 , wherein
 the total controller is configured to perform a retry control so that the rotating speeds of the first fan motor and the second fan motor are adjusted to the set rotating speed when the tuning control of rotating speed is performed for a predetermined time.   
     
     
         6 . The fan filter unit according to  claim 5 , wherein
 the total controller is configured to stop the fan motors when the retry control is repeated a predetermined times within a predetermined period of time.   
     
     
         7 . The fan filter unit according to  claim 1 , wherein
 the total controller is configured to stop the first fan motor and the second fan motor when any of a difference between the set rotating speed and the rotating speed detected by the first detector, and a difference between the set rotating speed and the rotating speed detected by the second detector is larger than a predetermined value.   
     
     
         8 . The fan filter unit according to  claim 1 , wherein
 the total controller is configured to stop the first fan motor and the second fan motor when a difference between the set rotating speed and the rotating speed detected by the first detector and a difference between the set rotating speed and the rotating speed detected by the second detector are larger than a predetermined value, respectively.