Air flow meter

Abstract

The present disclosure provides an air flow meter capable of measuring a flow rate of air in a main passage with high accuracy even in an environment where pulsation of air in the main passage increases. The air flow meter includes a flow rate detection element, a calculation unit 121, a signal extraction unit 122, a first correction unit 123, and a coupling unit 124c. The flow rate detection element is installed in a sub-passage that takes air from the main passage and returns the air to the main passage, and outputs a detection signal DS corresponding to a flow rate of the air flowing through the sub-passage. The calculation unit 121 generates a detected flow rate Qo as an output signal corresponding to the flow rate of the air flowing through the main passage based on the detection signal DS. The signal extraction unit 122 extracts an AC component Qhpf of the detected flow rate Qo which is an output signal. The first correction unit 123 outputs a first correction amount Q1 that corresponds to a half-wave rectified wave of the AC component Qhpf and increases according to an increase in a pulsation amplitude ratio of the AC component Qhpf. The coupling unit 124c subtracts a correction amount CA based on the first correction amount Q1 from the detected flow rate Qo as the output signal.

Dependencies are inferred from the claim text.