METHOD AND DEVICE FOR MEASURING FLOW VELOCITY OF FLUID

A method and an apparatus are disclosed for determining the flow rate of a flowing medium such as the amount of air supplied to an internal combustion engine. The apparatus includes at least one temperature-dependent resistor arranged in the flowing medium. For this purpose, an arrangement is provided which applies a quantity dependent on at least the flow rate to the temperature-dependent resistor. The method includes the step of abruptly reducing the flow rate dependent quantity to a value such as approximately zero in the presence of a flow-rate value lying below a predeterminable threshold value. Because the reduction takes place only for a predetermined period of time, normal operation will be resumed automatically when the flow rate rises again. A hot-wire air-flow sensor is arranged in the intake pipe of an internal combustion engine and the output signals thereof are a measure of the amount of air inducted by the internal combustion engine.