PURPOSE: To avoid errors of the measurement results caused by the back flow of a medium and measure the air intake quantity without using a region characterized by being pulsed by installing an additional heating element in the downstream side of a measurement sensor in an air intake pipe and heating a heating element in an average load state or a relatively high load state of an internal combustion engine.
CONSTITUTION: A temperature sensor resistor Pt, a sensor heating resistor Ph, and an additional heating resistor Rz are installed in this order from the upper stream along the intake air flow P in an air intake pipe. In the full load or at the beginning of the full load, the flow is strongly pulsed and constantly flows in the regular direction and forms a temperature boundary layer LV. This phenomenon is utilized to throw the resistor Rz in. Then, in the case of the full load accompanied with back flow, the resistor Rz is continuously heated. Air which is heated and flows backward is again lead to the resistor Rh and the air measured excessively in the regular direction is canceled. After that, in the case of the full load at high rotation speed, the flow speed is so quick that back flow is not possible and intake air swirls fiercely and the heat radiation is increased. That is compensated by throwing in the resistor Rz.
WO/2009/054940 | FLUID FLOW RATE SENSOR AND METHOD OF OPERATION |
JPH0758212 | [Title of Invention] Flow Sensor |