| 摘要 |
PURPOSE:To prevent overheating in the event of any abnormality by monitoring operation of a controlling transistor, which quickens the speed of a motor operated fan steppedly with the rising temp. of the radiator water, and by allowing the fan to rotate at a high speed at the time of abnormality being sensed. CONSTITUTION:One end of a temp. sensor 10 such as a thermistor is connected with the power supply B while the other end is grounded through resistances 11-13 in series connection. When the cooling water temp. for the radiator rises to cause drop of the resistance value of the thermistor 10, comparators 21-23 emit outputs one after another, and transistors 31-33 are actuated one after another. Consequently current is supplied to coils 51a, 51-53 of the motor through normally closed relays 41-43, and the revolving speed of a motor operated fan is going to increase. Logical circuits 61-63 monitor the voltage between the base and collector of transistors 31-33, and in the event of any abnormality a transistor 70 is deactuated to supply current to all of the motor coils 51-53. Now the fan rotates at a high speed. |
