US Patent 7565255 Thermal flow meter and control system

In regard to an output of an intake flow meter for an internal combustion engine, a pulsation error can be reduced and dispersion in correction at the time of correction of response delay (a recovering of response delay) is reduced. A digital device is used for pre-processing of a control unit for inputting a flow rate measuring signal. An output voltage of the flow sensor is converted into a digital value, the digital value is converted into a flow rate and adds a response delay. The control unit detects a degree of response delay in reference to dispersion in a clock signal so as to perform response delay recovering and reduce dispersion of the response delay.