Air-Flow Direction Detector System
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
An air-flow direction detection system comprises a probe having thermally sensitive resistors on opposite sides of a dielectric plate positioned in a hollow tube located in an air duct. Air is directed to flow over the resistors which are connected in a bridge circuit such that reverse air flow and flow cessation can be detected. As shown in Fig. 1, the probe comprises resistors RX1 and RX2 deposited on opposite sides of plate 10. RX1 and RX2 are made of the same high temperature coefficient of resistance materials. Plate 10 is made of phenolic or other heat-insulating material. RX1 and RX2 have finger sections 11 extending from base 12, as shown in the enlargement in Fig. 2, to provide greater temperature sensitivity. The probe is placed in a tube 13 located within an air duct formed by walls 14 (Fig. 3).