Patent ID: 8909486

Claim:
A flow measuring device adapted to be attached to a flow passage, the flow measuring device comprising: a flow rate detecting part that is configured to detect a flow rate of air flowing through the passage and to output a flow voltage signal, which is a voltage in accordance with the flow rate; an analog/digital conversion part that is configured to convert the flow voltage signal from the flow rate detecting part into digital data, which is flow digital data; a signal processing part that is configured to perform calculation processing upon the flow digital data, which includes averaging of a predetermined number of consecutive pieces of the flow digital data, and to output the averaged flow digital data as a flow rate signal, wherein: the predetermined number is equal to or larger than two; and the signal processing part averages the predetermined number of consecutive pieces of the flow digital data by means of moving average; a reference voltage generating art that is configured to output a plurality of reference voltage signals used for correction processing of the flow voltage signal; and a multiplexer that is configured to sequentially select the plurality of reference voltage signals and the flow voltage signal in a predetermined order, wherein: the flow voltage signal is selected between two adjacent reference voltage signals of the plurality of reference voltage signals; the analog/digital conversion part sequentially samples the plurality of reference voltage signals and the flow voltage signal in the order of the selection thereof by the multiplexer, and converts the plurality of reference voltage signals and the flow voltage signal into digital data so that each of the plurality of reference voltage signals is respectively A/D converted and the flow voltage signal is also A/D converted; and the signal processing part corrects the flow digital data using a linear correction equation that is set based on the digital data of the plurality of reference voltage signals, which are obtained by the analog/digital conversion part.