| 摘要 |
<p>PURPOSE:To detect air flow rate over a wide range by setting the heating temperature of a heating resistor on the basis of a detected intake air temperature and the heating current of the heating resistor. CONSTITUTION:The output of an air temperature detecting resistor 3 and the heating current of a heating resistor 1 are read by a microprocessor 5. From these values, the heating temperature of the heating resistor 1 stored in a ROM 6 is read, and the heating temperature of the heating resistor 1 is also calculated from the terminal voltage and heating current of the heating resistor 1. When the calculated temperature is lower than the value read from the ROM 6, the current of the heating resistor 1 is increased through a D/A converter 7. When the calculated temperature is higher than the value read from the ROM 6, the heating current is conversely reduced. Such an operation is repeated to keep the temperature of the heating resistor 1 at a determined temperature. Since the heating current changes according to the air flow rate when the air flow rate is changed in this state, an air flow rate signal can be provided.</p> |
