| 摘要 |
PURPOSE:To supply the stabilized amount of air and obtain the optimum air-fuel ratio, by controlling the driving current and the number of rotation of a fan motor automatically to keep the work done of the fan motor constant. CONSTITUTION:A current control circuit 8 compares a number-of-rotation control voltage 5, outputted from a micro-computer control circuit 9, with the output voltage of a current detecting circuit 7 and controls an electric power control circuit 4 so as to keep current, flowing through the current detecting circuit 7, constant. A micro-computer control circuit 9 reads information on the amount of combustion, operates the rotating number of an exhaust fan, which is determined by a formula related to a preset amount of combustion and the amount of supplied air, and controls the number-of-rotation control voltage 5 so that the number of rotation, read out of the output of the rotating number detecting device 2, becomes equal to the number of rotation operation by the circuit 9, whereby the fan motor 1 may be driven in constant rotation. The fan motor 1, driven by a constant rotation torque, achieves a constant work done and the exhaust fan is operated also by a constant work done, therefore, the stabilized amount of air may be supplied. |
