Patent ID: 6763711
Filing Date: 2004-07-20
Classification: G01F

Abstract:
An air flow sensor comprising:a temperature dependent resistor device; a first circuit for applying a voltage to the temperature dependent resistor device until it reaches a first temperature, the first circuit including: a first reference resistance leg; a first variable resistance log including the temperature dependent resistor device; and a first comparator connected to both legs for determining when the temperature dependent resistor device reaches the first temperature; a second circuit including: a second reference resistance leg; a second variable resistance leg including the temperature dependent resistor device; and a second comparator connected to both legs for determining when the temperature dependent resistor device reaches a second temperature; and a processor connected to both the first and second comparators and programmed to time the period of time it takes the temperature dependent resistor device to change from the first temperature to the second temperature to determine the heat loss rate of the temperature dependent resistor device.