Air flow measurement apparatus

An air flow measurement apparatus comprising:

• a signal processing unit comprising:
• (a) a flow detector including a flow sensor configured to detect air flow through a flow passage, the flow detector configured to convert an output signal of the flow sensor into a voltage;
• (b) a temperature detector including a temperature sensor configured to detect a temperature of the air flowing through the flow passage, the temperature detector configured to convert an output signal of the temperature sensor into a voltage;
• (c) a reference voltage generator configured to output a plurality of reference voltage signals used for a correction applied to a flow voltage signal that is the output signal of the flow sensor;
• and
• (d) an A/D converter including a multiplexer configured to sequentially select the flow voltage signal, the plurality of reference voltage signals, and a temperature voltage signal that is the output signal of the temperature sensor in a predetermined order, the A/D converter configured to sequentially sample and convert the flow voltage signal, the plurality of reference voltage signals, and the temperature voltage signal into digital data in the order selected by the multiplexer, wherein
• the signal processing unit applies a calculation or the correction to the digital data of the flow voltage signal by using the digital data of the plurality of reference voltage signals and the temperature voltage signal, the signal processing unit including a sampling timing setting section configured to set sampling timings at which the A/D converter samples the flow voltage signal, the plurality of reference voltage signals, and the temperature voltage signal, and
• the sampling timing setting section sets the sampling timings in such a manner that the sampling timing at which the air flow voltage signal is sampled is interposed between the sampling timings at which each successive two of the plurality of reference voltage signals and the temperature voltage signal are sampled.