Hot Wire Air Flow Meter for Engine Control Systems

A new type hot wire probe has been developed for measurement of intake mass air flow rate in electronic fuel injection systems. The probe was composed of a coiled platinum wire covered with a glass-ceramic composite material. Improvement in response time has been achieved through the reduction of heat transfer from the hot wire probe to the leading wires, resulting from low thermal conductivity of the covering material. The decrease of the longitudinal heat flow rate has been revealed by the measurement of temperature distribution in the probe.