Air movement measuring apparatus

Claim 1

A gaseous movement sensing apparatus comprising: an ultrasonic wave transmitting and receiving transducer means comprising a common support having along a central axis thereof a central support element with a conical outer surface, the vertex of which lies along said axis and defines the forward direction of said apparatus, said conical surface having three transmitting transducer elements mounted in the surface thereof and displaced relative to each other by approximately 120°, said three transmitting transducer elements each facing outwardly and in a forward direction relative to said central axis so that each of said transmitting transducer elements when mounted within said conical surface will be facing directly into the path of the gas whose movement is being sensed, three separate ultrasonic receiver transducer means each separately carried by said common support and spatially positioned about said central support element and each aligned with one each of said transmitting transducer elements along a line extending perpendicular from said conical surface, each of said receiver transducer means being flush mounted within the side of a separate elongated streamlined housing, carried by said common support, and each of said receiver transducer means when mounted facing toward its corresponding transmitting transducer element; an ultrasonic wave energy source connected to said transmitting transducer elements to energize said elements to project ultrasonic wave energy in one direction only from each of said transmitter transducer elements toward each corresponding one of said receiver transducer means; and means connected to said receiver transducer means to measure the time difference in the received signals received by said receiving transducer means and thereby the movement of a gaseous medium relative to said sensing apparatus.