Air flow rate meter for internal combustion engine of vehicle, has digital section determining ratio when air flows into duct and another ratio when air in duct flows in one direction, where former ratio is greater than latter ratio

摘要

The meter (1) has a sensor section (2) arranged in an air duct. A digital section (5A) includes an analog/digital converter (17) to convert analog voltage output by the sensor section into a digital value. The digital section determines a conversion ratio of a frequency value relative to a change of the digital value, when air flows into the duct in a normal direction. The digital section determines another conversion ratio of the frequency value relative to the change of the digital value when the air in the duct flows in a reverse direction. The former ratio is greater than the latter ratio.