Patent ID: 7587938

Claim:
A thermal gas-flow measuring instrument comprising: a first heating resistor placed in a gas to be measured in an exhaust atmosphere; a temperature sensing resistor positioned at upstream side or downstream side of the heating resistor, for measuring the flow rate of the gas; and a second heating resistor to suppress the heat transfer from the heating resistor to a support for supporting the first heating resistor; wherein the second heating resistor is positioned between the first heating resistor and the support for supporting the first heating resistor, and the second heating resistor is electrically insulated from the first heating resistor; and wherein the temperature of the first heating resistor and the temperature of the second heating resistor are set so that the temperature range in a zone between the first heating resistor and the second heating resistor becomes at or above the temperature at which a water droplet contacting with the surface of the zone is evaporated to disappear by film boiling.