| 摘要 |
PROBLEM TO BE SOLVED: To prevent the burning of a motor by preventing an overcurrent in a motor with its rotating speed changing according to a feeding voltage, even when a load of the motor is suddenly made constraint. SOLUTION: A DC motor 25 used for air cleaning, a speed sensor 21 for detecting the rotating speed of the DC motor 25, and a voltage adjusting circuit 23 for adjusting a motor feeding voltage V0 on the basis of the detected data of a motor rotating speed, and a comparator 27 for comparing a reference voltage Vref necessary for setting a given motor rotation speed with the motor feeding voltage V0 adjusted by the voltage adjusting circuit 23. In addition, a current limiting circuit 26 for adjusting a motor feeding current Im based on the potential difference detecting signal S5 is provided. As a result, the motor feedign current Im can be set automatically according to the change in the motor feeding voltage V0. |
