Patent ID: 9719836
Date: 2017-08-01
CPC Classifications: F02D,G01F

Claim:
1. An air flow measuring device for producing an intake air amount detection signal and an intake temperature detection signal which indicate a flow rate and a temperature of intake air drawn into an internal combustion engine, respectively, the air flow measuring device comprising: a housing that projects into an intake passage through which the intake air flows and that includes an internal passage which takes in a part of intake air flowing through the intake passage and through which the part of intake air passes; a high-temperature resistance that is disposed in the internal passage and has its energization controlled in accordance with the flow rate of intake air flowing through the internal passage to increase or decrease an amount of heat generated; a first low-temperature resistance that is an element constituting a bridge circuit which has its energization state changed according to the amount of heat generated by the high-temperature resistance, wherein the first low-temperature resistance varies its resistance value according to the temperature of intake air; a second low-temperature resistance that is an element, which is not incorporated into the bridge circuit and varies its resistance value according to the temperature of intake air to increase or decrease an amount of energization; a predetermined substrate on which the second low-temperature resistance is provided as a semiconducting or metallic film; another bridge circuit that produces the intake air amount detection signal by use of an electrical signal generated by operation of the high-temperature resistance and the first low-temperature resistance; and a digital circuit that uses an electrical signal produced by the second low-temperature resistance as the intake temperature detection signal.