Pressure sensor for counting and control of traffic - utilises pressure chamber containing linear magnetic hall effect sensor and rubber membrane with screw-adjusted pre-tension

摘要

A pressure sensor allows brief pressure variations to be counted to permit counting and control of traffic. The sensing is performed by a Hall effect linear magnetic sensor and an electronic circuit allows slow changes such as temperature and atmospheric pressure to be accounted for. A pressure chamber (10) contains a rubber membrane (11) preadjusted for tension by a hollow screw (12). The membrane is glued to a very light magnetic rubber element (13) which is opposite a linear Hall effect sensor (16) mounted on a printed circuit board (15). A flexible tube (14) is subjected to passing vehicle wheels and enters the pressure chamber. As vehicles pass the membrane is deformed to generate a voltage variation at the sensor output. This is processed by a electronic circuit.