Patent ID: 8669730
Filing Date: 2014-03-11
Classification: F24F,H02P,Y02B

Abstract:
1. A ventilating system that can make an air flow rate variable, comprising: a DC motor that drives blades in a main body; and a control drive IC that is built in the DC motor and controls the DC motor, wherein a control circuit in the main body includes a first current detecting unit that detects a current flowing in the DC motor, a second current detecting unit that detects a motor drive current that flows in the control drive IC and drives the DC motor, a rotating speed detecting unit that detects a rotating speed of the DC motor, and a control unit that controls the DC motor based on the rotating speed detected by the rotating speed detecting unit, the current detected by the first current detecting unit and the current detected by the second current detecting unit, and the first current detecting unit includes a plurality of low-resistance resistors and detects the current flowing in the DC motor by switching the low-resistance resistors, and calculates a ventilation air flow rate from the rotating speed detected by the rotating speed detecting unit and a current value calculated by subtracting the current detected by the second current detecting unit from the current detected by the first current detecting unit.