Ultrasonic Air Temperature Sensing for Automatic Climate Control - Sensor Development

Automatic climate control could be improved by measuring air temperature ultrasonically. Thermal comfort correlates better with bulk air temperature than with the temperature measured by the in-car sensor. The time of flight of an ultrasonic pulse through the air gives the bulk air temperature. In a proof-of-concept experiment, it is accurate to ± 0.5 °C from -40 to+60 °C. Two operational modes are demonstrated: pulse-echo in which a single transducer creates a pulse and detects its return from a reflector, and single-pass in which a source transducer creates a pulse that travels directly to a separate transducer.